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April 4th, 2014.
The music in her ears was slow, aching—the kind that seeped into the cracks of a shattered heart and made a home there. Outside the train window, the nighttime world blurred past in vibrant shades of black and blue, affecting her gloomy mood. The rhythmic clatter of the tracks beneath her feet was almost soothing, a steady counterpoint to the quiet storm inside her chest.
It was the last day of school for most students in Japan, and for the broken-hearted girl on the empty train, it felt like the end of something far greater.
She watched the waves crash against the shore in the distance, their relentless motion both beautiful and cruel. The sea didn’t care about endings. It didn’t care about goodbyes. It simply was—eternal, indifferent. The glass of the train window was cool against her forehead as she leaned closer, her breath fogging the pane for just a moment before fading away.
Like memories. Like promises.
A soft chime announced the next stop, and the girl exhaled, her fingers tightening around the strap of her bag. She hadn’t meant to take this train. Hadn’t meant to end up here, alone, with nothing but the echoes of a voice she’d never hear again.
But here she was.
And as the train slowed to a stop, she made a decision.
She stepped onto the platform, the salt-kissed wind tangling in her blue-dyed hair. The station was nearly deserted, the kind of place people passed through but never stayed.
The wind off the sea was sharper than she’d expected.
The girl—her name long since buried under the weight of ex-girlfriend, third-year, soon-to-be-adult—kicked off her loafers at the edge of the sand, letting her socks grow damp as she trudged forward. The beach was empty, save for the gulls wheeling overhead and the distant pulse of waves folding into themselves. The kind of place people came to disappear.
Perfect.
She fished a cigarette from the crumpled pack in her blazer pocket, the paper already slightly bent from earlier attempts. The wind snatched at her lighter’s flame the second she flicked it, hissing like it was laughing at her.
“Tch.” She cupped her hands tighter, turning her back to the breeze. Three tries. Four. On the fifth, the tip finally glowed orange, and she inhaled like she was stealing fire from the gods.
The smoke burned in her lungs, familiar and bitter.
Three years.
Three years of stolen glances between classes, of tangled fingers under desk lids, of whispered promises against her neck in the stairwell where no teachers patrolled. Three years of believing, stupidly, that love was something that could last.
And then, on a Tuesday no different from any other, he’d said it: “I think we should see other people.”
As if they were menu options. As if her heart wasn’t stapled to his.
She exhaled hard, watching the smoke unravel into the twilight.
“You know those’ll kill you, right?”
The voice came from her left—small, matter-of-fact, entirely unimpressed.
She turned. A boy, no older than ten, was crouched beside a tripod-mounted telescope, adjusting its lens with the precision of a watchmaker. His hair stuck up in odd angles, as if he’d forgotten to brush it for a week, and his oversized hoodie swallowed his frame whole.
She blinked. “What?”
“Cigarettes.” The boy didn’t look up. “The tar coats your alveoli, reducing lung capacity by up to thirty percent in long-term users. Also, nicotine’s addictive and a vasoconstrictor. Basically, you’re paying to choke yourself slowly.”
A beat. Then—
She laughed.
It burst out of her, sharp and unexpected, like a cork from a bottle. The boy finally glanced up, eyebrows raised.
“What?” he said, echoing her earlier tone.
“Nothing.” She wiped at her eye with the heel of her palm. “Just—you’re ten. Why do you sound like a medical textbook?”
“I’m ten and a ninety days,” he corrected, nose scrunching. “And knowledge isn’t age-restricted.”
She took another drag, grinning now. “You ever smoked?”
“No.”
“Then you don’t know the best part.” She tilted her head. “It feels good. Takes the edge off.”
The boy—Ishigami Senku, probably, she thought, judging by the name stitched sloppily onto his backpack—frowned. “So does deep breathing. And that’s free.”
She snorted. For a kid, he had the cadence of a grumpy old man.
The wind picked up again, sending sand skittering across her ankles. She shivered, suddenly aware of how thin her uniform shirt was. Without asking, she plopped down beside him, folding her legs to her chest.
Senku stiffened but didn’t protest.
For a while, they sat in silence—her smoking, him fiddling with his telescope’s focus knob. Up close, she could see the careful way he handled the equipment, fingers steady despite their smallness. A scientist in the making.
“What’re you looking at?” she asked, nodding at the telescope.
“Jupiter.” He adjusted a dial. “Its moons are visible tonight. Io’s volcanic activity makes it the most geologically active body in the solar system. Ten times cooler than Saturn’s rings.”
She hummed, flicking ash onto the sand. “Sounds like you’ve got a favorite.”
“It’s just facts.” But there was a flicker of pride in his voice.
She studied him sidelong. Most kids his age would be inside playing video games, not setting up telescopes alone on a chilly beach.
“Your parents know you’re out here?”
“Byakuya at a conference. He lets me do independent research.” Senku finally looked at her, red eyes sharp behind his bangs. “What about you? Shouldn’t you be at, like, a party or something?”
The cigarette between her fingers suddenly felt heavier.
“Not really my scene.”
“Hmph.” He turned back to the eyepiece. “You’re weird for a high schooler.”
“Takes one to know one, elementary-schooler.”
He shot her a glare, but there was no heat in it.
The waves filled the quiet between them. She watched the ember of her cigarette pulse with each inhale, like a tiny, dying star.
“Hey,” she said after a while. “You ever been in love?”
Senku nearly dropped his lens cap. “What?”
“Just wondering.” She smirked at his horrified expression. “You seem like the type to calculate romance like a math problem.”
“Romance is just oxytocin and dopamine reactions. It’s biology.” He crossed his arms. “And no. I’m not wasting time on that until I’m at least thirty.”
She laughed again, softer this time. “Smart kid.”
He bristled. “I’m not a—”
“You ever been dumped, then?”
The question slipped out before she could stop it.
Senku paused. For the first time, his confidence wavered. “…No.”
She nodded, staring at the horizon. “Lucky you.”
The wind carried her smoke away, scattering it into nothing.
Senku chewed his lip, then suddenly shoved the telescope toward her. “Here.”
She blinked. “Huh?”
“Jupiter’s brighter tonight than it’ll be for another month. You should look.” His tone was gruff, as if offering comfort physically pained him. “It’s… distracting.”
For a second, she just stared at him. Then, slowly, she stubbed out her cigarette and leaned forward, pressing her eye to the viewfinder.
A tiny, brilliant sphere greeted her, striped in creams and browns, flanked by four pinpricks of light.
“Whoa.”
“That’s Io, Europa, Ganymede, and Callisto,” Senku said, pointing at each moon in turn. “Over three hundred million miles away, and we can still see them.”
She didn’t reply. Something in her chest ached—not the sharp, suffocating pain of heartbreak, but something quieter. Something like wonder.
Senku watched her, then awkwardly cleared his throat. “You can stay and watch, if you want. I’ve got extra notes.”
She glanced at him. “You’re not gonna lecture me about smoking again?”
“I’m eighty percent sure you won’t do it near my equipment.”
She grinned. “Deal, kid.”
December 23rd, 2014.
The bus window was cold against the girl’s cheek, the glass fogging slightly with each breath. Outside, the city was a blur of white—snowflakes spiraling down from the black sky, melting against pavement, clinging to the shoulders of strangers hurrying home. Christmas lights glowed from storefronts and lampposts, red and green and gold, their reflections smeared across the wet streets like spilled paint.
She didn’t know where she was going.
Her parents were overseas again—her father on another business trip, her mother visiting relatives in a half-hearted attempt to pretend their marriage wasn’t crumbling. It didn’t matter. Even if they were in Japan, they’d just be in different rooms, voices sharp through paper-thin walls.
“Why can’t you just—”
“You never listen—”
“I’m so tired of this—”
The despaired girl exhaled, watching the condensation bloom and fade on the glass.
The bus shuddered to a stop, and she stepped out into the snow.
The city was alive in a way that made her loneliness feel heavier.
Everywhere she looked, there were families. A father lifting his daughter onto his shoulders to see a department store’s light display. A couple sharing a scarf, their laughter puffing out in white clouds. A group of teenagers shoving each other playfully, their shopping bags swinging.
She shoved her hands deeper into her coat pockets and walked faster.
She didn’t know where she was going. She just knew she couldn’t stand still.
The music from street speakers was too cheerful—jingle bells and sleigh rides and joy to the world. She turned down a quieter side street, then another, until the noise faded into the background. The snow was thicker here, untouched by footprints.
And then, a park.
Small, half-forgotten, tucked between buildings like an afterthought. The swings creaked faintly in the wind, their chains rusted. She brushed snow off one and sat down, the cold metal biting through her skirt.
She tipped her head back.
The sky was dark, the stars smothered by city lights and snow clouds. But for a moment, she pretended she could see them—Jupiter, Io, Europa, the constellations that one kid had pointed out to her that night on the beach.
Eight months ago.
Had it really been that long?
She dug the toe of her boot into the snow, dragging the swing back slightly. The chains groaned in protest.
Then—
“You’re the blue-haired girl from the beach.”
The girl yelped, losing her balance. The swing tipped backward, and she landed hard in the snow, blinking up at the figure now looming over her.
Red eyes. Messy hair. A hoodie that looked even thinner than the last time she’d seen him.
Senku stared down at her, unimpressed.
The despaired girl burst out laughing.
“What the hell are you doing here?” She sat up, brushing snow off her sleeves.
“Collecting samples.” He held up a small vial filled with snow. “Different districts have varying levels of air pollution. The crystalline structure changes because of it.”
She squinted at him. “It’s Christmas Eve Eve. Shouldn’t you be, like, eating cake or something?”
Senku shrugged. “Cake is just sugar and flour. Science is eternal.”
The girl snorted.
Senku eyed her. “Did you get over your ex?”
The question was so blunt it caught her off guard. She blinked, then smirked. “Yeah. Turns out he wasn’t the center of the universe.”
“Statistically improbable anyway,” Senku muttered.
She laughed again, softer this time.
The wind picked up, slicing through the park. Senku shivered visibly, his shoulders hunching.
She frowned. “You’re freezing.”
“It’s fine. The human body can withstand—”
“Oh my god.”
She grabbed his hands before he could finish.
His skin was like ice—not just cold, but rigid, the kind of cold that seeped deep into bone. His fingers were stiff, slightly red at the knuckles, the way hands got when they’d been clenched too long in the cold. Without thinking, she turned them over in hers, her thumbs pressing into his palms as if she could jumpstart warmth back into them.
She rubbed his hands between hers until more of the color returned, then unwound her scarf—thick, knitted, dark blue—and looped it around his neck. It drowned him, the ends hanging almost to his knees.
Senku stiffened. "W-What are you—"
"Shut up," she said, but there was no bite to it.
She cupped his hands between hers, forming a hollow space—a little shelter—and brought them close to her mouth. Her breath unfurled in a slow, steady stream, warm and damp against his skin. She could feel the exact moment the heat reached him: the slightest twitch of his fingers, the way his pulse fluttered under her touch.
Senku didn’t pull away. He didn’t even complain.
She grinned. “What? No scientific rant about how scarves are just woven fibers?”
Senku opened his mouth. Closed it. Looked away. His nose was still pink from the cold.
She tilted her head.
Before she could tease him, Senku abruptly crouched, scooping up another vial of snow. “A-Anyway! The particulate matter in this area is—”
She let him ramble, smiling to herself as she sat back on the swing.
The snow kept falling. The city kept glowing.
February 7th, 2016.
After graduating high school, she had taken the first opportunity to disappear. A job as an assistant on a cargo ship, eighteen months at sea, hopping from port to port. The pay was decent, the ocean was endless, and best of all, the people were real. No fake smiles, no hidden agendas—just sailors and deckhands who said what they meant and meant what they said.
Eighteen months at sea had rewired her sense of balance. Even now, standing on solid concrete in Yokohama’s bustling port, her body instinctively braced for the roll of waves that never came. The scent of diesel and fish guts clung to her jacket—a smell that would’ve made her gag two years ago but now felt as familiar as her own skin.
She adjusted the duffel bag slung over her shoulder, its contents sparse: some clothes, a few trinkets from various ports, and the waterproof journal she’d filled with messy notes and even messier sketches. The crew had teased her about it. "You gonna write a novel, kid?" But there was something about watching the sun rise over the Timor Sea or seeing bioluminescent algae light up the Blackwater off Malaysia that made her want to trap those moments on paper before they slipped away.
Four months of shore leave. Four months to remember what it was like to be a person instead of just part of a crew.
Her aunt—an aging widow with a too-big house—had rented her an apartment for practically nothing. "Just don’t throw parties," she had said, as if the girl had ever been the type. It was cheap, and more importantly, it was hers.
She dumped her bag on the futon and immediately set about making the space livable. She cracked the window to air out the mildew, tacked up a map of the world she’d stolen from the ship’s mess hall, and taped her favorite polaroids along the edges:
-
Singapore at dawn, the skyline smudged pink and gold.
-
A street vendor in Manila, grinning toothlessly as he handed her a skewer of unidentifiable meat.
-
The crew of Hanoi, crammed into a too-small lifeboat during a drill, flipping off the camera.
She was halfway through scrubbing years of grime off the mini-fridge when her phone buzzed. A text from Ryota, the ship’s electrician:
"Made it to Osaka. Mom cried. Dad asked when I’m getting a real job. You?"
She wiped her hands on her jeans before replying: "Living the dream. My palace has two cockroach roommates."
She tossed the phone aside and reached for the bread she’d bought earlier, tearing into the loaf like she was still on rations.
The next morning, the girl wandered toward the river, drawn by habit more than anything. Back on the ship, this had been her time—0500 hours, when the night shift was ending and the day shift hadn’t fully woken up yet. She’d sit on the bow with her journal, watching flying fish skitter across the waves.
Here, the river was sluggish and brown, flanked by concrete embankments. But the quiet was the same.
That’s when she spotted the kid.
At first, she thought he was some middle schooler skipping class to mess around with scrap metal. Then she recognized the wild hair, the too-bright eyes, the way his fingers moved with precision that bordered on obsessive.
"Tenkyu? Renku? Ah—Senku!"
No reaction.
She tromped down the slope, her boots kicking up gravel. "Wow. Cold shoulder right out the gate, huh?"
Senku finally glanced at her, his red eyes flickering with something like recognition—but not quite.
She sighed dramatically. "Should I dye my hair blue again?"
That did it. His eyebrows lifted slightly. "…The beach. And the park."
"Bingo." She smirked. "You do have a memory in that science-filled head of yours."
Senku turned back to his generator, adjusting a wire. "I never got your name."
"(Y/n)." She held out the bread bag. "Want some? It’s fresh."
He shook his head. "I’m in the middle of calibrating this."
"Uh-huh." She tore off a piece and popped it into her mouth. "So, what’s this thing supposed to be?"
"A thermoelectric generator. Converts heat differentials into electricity." He tapped a metal plate. "It’s for my school’s science fair."
"Fancy." She leaned closer. "Your parents gonna show up?"
Senku’s hands stilled for half a second before he reached for a screwdriver. "Doubt it. They’re busy." His tone was flat, deliberate. "Why are you here?"
She recognized the deflection but let it slide. "Got a few months off before my next trip. Figured I’d crash in my aunt’s place." She nodded at the generator. "Need a test subject? I’m great at standing around and looking impressed."
Senku snorted. "You’d be terrible at it."
"Rude."
He glanced at her, then held out a hand. "Give me the bread."
She laughed and handed it over.
Senku eyed it suspiciously before taking it. "You’re weirder than I remember."
"Eighteen months at sea does that to a person."
The river murmured beside them, the generator hummed faintly, and for a moment, it almost felt like coming home.
February 12th, 2016.
The gymnasium of Senku’s middle school buzzed with the chaotic energy of a science fair in full swing. Colorful tri-fold posters lined the walls, decorated with glitter-glue titles and printed graphs. Students in pressed uniforms stood proudly beside their projects, flanked by beaming parents who snapped photos on their phones. The air smelled of disinfectant and the faint, greasy aroma of microwave popcorn from the concession stand.
Senku sat alone at his assigned table, his thermoelectric generator humming quietly under the fluorescent lights.
It was objectively the most impressive project in the room—a fully functional device that converted waste heat into usable electricity, its copper coils gleaming under the glass casing he’d fashioned from a repurposed aquarium. The teachers who stopped by marveled at it, their eyebrows climbing toward their hairlines.
“This is university-level work,” Mr. Fujimoto, the physics teacher, muttered, crouching to examine the wiring. “How long did this take you?”
“Six days, and approximately fourteen hours,” Senku said flatly.
The teacher chuckled, mistaking his precision for humor. “Well, your parents must be—” He caught himself, his smile faltering. A beat of awkward silence. “Ah. Right.”
Senku didn’t react. He’d long since mastered the art of keeping his face blank when adults fumbled over his lack of parents.
Across the aisle, a cluster of students erupted into laughter. Senku glanced over just in time to see Yamada-kun’s father sling an arm around his son’s shoulders, grinning as he pointed at some botany experiment. The boy’s cheeks flushed with pride.
Senku looked away.
It wasn’t that he cared about parental approval. He didn’t. Approval was an emotional variable, and emotions were inefficient. But,
(But sometimes, in the quietest corners of his mind, he wondered what it would be like to have someone there. Not to praise him—he didn’t need praise—but just to witness. To say, I saw what you made, and it existed outside your own head for once.)
“Wow, Ishigami, this is insane!”
A group of classmates had gathered around his table, their eyes wide. One of them—Takano, a girl who’d once asked him to “dumb down” his explanations during a group project—reached out to touch the generator’s casing.
Senku slapped her hand away without thinking. “Don’t. The surface temperature is 62.3 degrees Celsius. You’d blister your fingerprints off.”
Takano jerked back, scowling. “Jeez, sorry. No wonder you don’t have many friends.”
The group tittered, but their laughter died when Senku didn’t rise to the bait. He simply adjusted the generator’s output dial, his expression bored.
They wandered off eventually, whispering just loud enough for him to hear:
“It’s kinda sad, though. Like, his dad’s in space or whatever, but he never even visits—”
“I heard he’s basically an orphan—”
“Do you think he eats lunch alone every day because he wants to, or—”
Senku’s fingers tightened around his screwdriver.
Idiots. All of them.
He stood abruptly, chair scraping against the linoleum. He didn’t need to be here. The judging was over, and his victory was a foregone conclusion. He could—
“Senku!”
The voice cut through the gymnasium chatter like a knife.
He turned.
The girl from the beach, park, riverbank—stood in the doorway, her cheeks flushed from the winter cold, her breath still coming in little white puffs. Her boots left damp footprints on the floor as she strode toward him, completely ignoring the stares she drew.
“I had to check every single classroom, you know!” She planted her hands on his table, leaning in. “You never told me what room you were in!”
Behind her, Senku’s classmates were whispering again, but the tone had shifted:
“Who’s that?”
“She looks like a model—”
“Is she his sister?”
Senku ignored them. “Why did you come anyway?” He aimed for nonchalance, but something warm and unnameable curled in his chest.
She grinned. “Wouldn’t miss it for the world.”
She circled the table, examining his generator with a sailor’s practiced eye for machinery. “Holy shit, you built this? Like, from scratch?”
“Obviously.”
“Senku, this is insane.” She tapped the glass. “Does it actually work?”
He flicked a switch. The generator whirred to life, its indicator lights flaring blue.
“No way.”
For the first time all day, Senku felt the corner of his mouth twitch. “Way.”
She threw an arm around his shoulders, ignoring his immediate stiffening. “You’re a freaking genius, you know that? Like, properly insane.” She turned to the gawking classmates. “Right? Right?”
The students nodded mutely.
Senku allowed himself a small, private smirk.
June 15th, 2016.
Cooking for Senku had become something of a ritual.
At first, it had been practical: she’d shown up unannounced one evening to find him elbow-deep in a homemade electromagnet, a single energy bar wrapper discarded on the floor like evidence of a failed self-care attempt. The sight had pissed her off so much she’d marched to the nearest konbini and returned with ingredients for proper curry.
Now, months later, she knew his kitchen better than her own.
The rice cooker beeped obediently as she stirred the miso soup, the steam fogging up the tiny window above the sink. Senku sat at the table, uncharacteristically quiet, picking at the tamagoyaki she’d slapped onto his plate.
“You’re leaving tomorrow.”
It wasn’t a question.
She didn’t pause in her stirring. “Yeah. 30-month contract this time.”
Senku’s chopsticks tapped against his bowl—once, twice. A staccato rhythm she recognized as his I’m-thinking-too-hard tell.
“You’ll be back,” he said, with the same certainty he reserved for stating the boiling point of water.
She smirked. “Counting the days already?”
“Don’t flatter yourself.” But his ears were pink.
After dinner, the girl tossed Senku his shoes. “Come on. Last ride.”
He groaned but followed anyway.
The motorbike was a recent development—a rusty secondhand thing she’d bought on a whim. For two straight nights, the girl worked on the bike in the cramped garage. She'd never been mechanically inclined, but eighteen months at sea had taught her the basics of maintenance. She polished the metal until it gleamed, fixed the bolts the front wheel, and replaced the headlight wiring with the ones she'd found at a hardware store.
Tonight's final ride began like all the others—with Senku clinging to her waist like his life depended on it.
"Slow down—slow down, you maniac—"
The girl only laughed and accelerated harder, the bike's wheels humming against the pavement. The wind tore at Senku's protests, stealing them away as they careened down the hill toward the riverbank.
She knew every bump in this route by now:
-
The Crack – A jagged fissure in the sidewalk near the 7-Eleven that sent them jolting upward. Senku's grip tightened instinctively, his chin knocking against her shoulder.
-
The S-Curve – A winding descent where she liked to lean into the turns, the bike tilting dangerously. Senku's knees pressed against her thighs, his breath hot on her neck. "If we die, I'm haunting you first."
-
The Jump – An unassuming ramp formed by a construction plate. She hit it at full speed every time, just to hear Senku's undignified yelp as they caught air.
She didn’t stop until the city lights were far behind them, until the only illumination came from the moon and the fireflies dancing over the paddies. The air here was sweet with young rice and damp earth.
Senku staggered off the bike, glaring. “You’re insane. We’re miles from—”
The girl sat on the hood of an abandoned tractor, patting the space beside her.
Senku shut up and sat.
For a while, they just listened to the night—the chirp of crickets, the distant croak of a frog, the whisper of rice stalks in the breeze.
Then, quietly:
“You can’t go.”
She turned.
Senku was staring at his hands, his shoulders hunched. In the moonlight, he looked younger than his twelve years—small and sharp-elbowed and fragile in a way that had nothing to do with physical strength.
“Senku—”
“It’s illogical,” he snapped, voice cracking. “The mortality rate for cargo crews is 0.8% annually, and that’s before factoring in—”
She pulled him into a hug.
He stiffened, then—
Then he broke.
It wasn’t loud. It wasn’t dramatic. But she felt it all the same—the way his breath hitched, the way his fingers twisted into her jacket like she might vanish if he let go.
“You’re less grown up than me,” he muttered, voice muffled against her shoulder.
She rested her chin on his head. “Yeah, yeah.”
“You’re reckless.”
“Uh-huh.”
“And you smell like diesel.”
“Sure do.”
Senku sniffed. “...Hurry back.”
She closed her eyes. “Promise.”
Above them, the stars wheeled on—unchanged, uncaring, as they had for millennia.
January 4th, 2019.
The digital clock on Senku’s desk blinked 23:47 in harsh red numerals.
Thirteen minutes left of his birthday.
He sat slumped on the floor of his apartment, back against the couch, staring at the slice of cake on the coffee table. It was store-bought—some overly sweet strawberry shortcake his classmates had shoved into his hands earlier with a chorus of "Happy 15th birthday, Ishigami!" The whipped cream had started to sag at the edges, the sad, wilted strawberry on top looking more like a surrender flag than decoration.
Senku poked at it with a plastic fork.
Four days.
Four days since her ship was supposed to dock. Four days of him not pacing by the harbor like some pathetic stray. Four days of him definitely not lingering near the train station after school, just in case.
(He’d calculated the logistics, of course. Accounting for potential delays—weather, customs, mechanical failures—a four-day discrepancy was well within the margin of error. Statistically insignificant.
And yet.)
The fork snapped in his hand.
A sharp knock at the door.
Senku’s head jerked up. His body moved before his brain could catch up—he was on his feet in an instant, heart hammering against his ribs. He forced himself to take a breath, smooth his expression, before yanking the door open with what he hoped looked like casual annoyance.
"Look, I already told you—"
A salesman stood on his doorstep, grinning like a used-car dealer. "Good evening, young man! Have you heard about our revolutionary Himalayan mineral water filtration system? It’s infused with—"
Senku’s grip on the doorframe tightened. "I built my own purifier. It’s twice as efficient as whatever overpriced scam you’re peddling."
The man blinked but barreled on. "Ah, but ours has healing properties! The ancient glaciers—"
"Not. Interested." Senku moved to slam the door.
The salesman wedged his foot in the gap. "Just one demonstration! Your skin will glow—"
He closed the door, now the salesman's voice muffled behind the wood.
A sharp knock at the door.
That damn salesman was persistent.
He yanked the door open.
And instead, there she was.
The girl who was always at sea, stood in the hallway, her face flushed from the cold, snow dusting her shoulders like powdered sugar. Her hair was much longer now. She looked smaller than he remembered—or maybe he had just grown taller.
In her hands was a small, carefully wrapped box.
"Happy birthday, Senku," she said, grinning.
For a moment, he just stared. His chest tightened in a way that had nothing to do with science.
"You're late," he said flatly.
She rolled her eyes. "Yeah, yeah. Customs held us up in Thailand. You gonna let me in, or are we doing this in the hallway?"
Senku stepped aside, and she brushed past him, kicking off her boots with practiced ease. She smelled like salt and engine grease and something faintly floral—probably some cheap soap from the ship.
"Here," she said, thrusting the box into his hands. "Open it."
Senku turned the package over. It was heavier than he expected, the wrapping paper slightly wrinkled, as if she’d tried and failed to make it neat. He peeled it back carefully, revealing a polished brass pocket watch.
Not just any pocket watch.
The casing was engraved with delicate, swirling patterns—celestial maps, equations, tiny constellations etched into the metal. When he flipped it open, the face was a miniature orrery, the planets orbiting the sun in precise, mechanical harmony. 23:56
Senku’s breath caught.
"I, uh, commissioned it from some artisan in Thailand. Took forever. The guy kept complaining about the tolerances, but I told him—"
Senku snapped the watch shut, cutting her off.
"It’s inefficient," he said. "A digital display would be more accurate."
She smirked. "Yeah, but it wouldn’t piss off your teachers as much when you pull it out in class."
Senku’s lips twitched. He turned the watch over in his hands, tracing the engravings. "You remembered."
She shrugged, but her smile softened. "Course I did."
A silence settled between them, comfortable and familiar. Outside, the wind rattled the windows again, but the apartment felt warmer somehow.
Senku cleared his throat. "You staying?"
She flopped onto his couch, stretching her arms behind her head. "For a while, yeah."
Senku nodded, as if this was just a casual observation and not something that sent a stupid, illogical rush of relief through him.
He glanced at the forgotten cake on the table. "You want some?"
She grinned. "Only if you’re not gonna eat all of it, fatty."
Senku flipped her off, but he was already reaching for a second fork.
September 30th, 2019.
The clock on the wall ticked past 4:17 AM when the front door finally creaked open.
She shot up from the kitchen table, where she’d been nursing a cold cup of tea for the past three hours. Her heart pounded—half from relief, half from simmering anger.
Senku stood in the doorway, his school uniform rumpled, leaves tangled in his hair. His eyes were shadowed, his expression unreadable. He looked like he’d been wandering through the woods all night.
Which he probably had.
Her grip tightened around the mug. “Where the hell have you been?”
Senku didn’t flinch. He just kicked off his shoes and walked past her like she wasn’t there.
That stung more than she wanted to admit.
She followed him into the living room. “You can’t just disappear like that! Do you have any idea how worried I—”
“Worried?” Senku spun around, his voice sharp. “That’s rich, coming from you.”
She froze.
Senku’s smile was bitter. “What was it you said back then? ‘I just needed to take the edge off’? Pretty hypocritical to criticize me for doing the same thing.”
The memory of that night on the beach—years ago now—flashed between them. The cigarette she couldn’t light, the waves, the way she’d lied through her teeth about being fine.
Her jaw clenched. “That was different.”
“How?”
“Because my life was shit back then!” The words burst out before she could stop them. “My parents hated each other, I hated myself, and I—” She cut herself off, shaking her head. “It’s not the same.”
Senku laughed—a harsh, brittle sound. “Oh, right. Because my life’s been so perfect? At least your parents stuck around long enough to fight.”
The air between them went electric.
She took a step back. “That’s not what I meant.”
“Then what did you mean?” Senku’s voice rose, his composure cracking. “Because it sure sounds like you’re trying to play mommy now that it’s convenient for you.”
The words hit like a slap.
She recoiled. “I’m not—”
“Then what are you?” Senku’s eyes burned into hers. “Why do you keep coming back? Why do you care?”
The question hung in the air, raw and unfiltered.
She opened her mouth—
And Senku kissed her.
It was clumsy, desperate, all teeth and pent-up frustration. His hands gripped her wrists, pinning them to nothing. For a split second, she couldn’t breathe.
Then—
Senku jerked away like he’d been burned. His face was pale, his breathing ragged. “I—shit—I didn’t mean—”
Her wrists throbbed where he’d held them. Her vision blurred.
Senku was trembling. “Hey, I’m sorry—”
She wiped her eyes with the back of her hand. “It’s fine.”
“It’s not fine.” His voice broke. “I hate this. I hate feeling like—like some kid you pity. Like I’m just another project to you.”
She swallowed hard. “You’re not.”
"Then stop treating me like I'm some child!" Senku's voice cracked, raw with frustration. "I'm not that lost kid on the beach anymore. I'm fifteen, (Y/n). I know what I want. And it kills me that you still look at me like I'm some helpless little kid, even though I'm—" He cut himself off, jaw clenching.
She stared at him, her chest tight.
Senku took a shaky breath. "Even though I'm taller than you now. Even though I could—" His hands flexed at his sides. "God, you still don't see me at all, do you? Seven years difference and you act like it's some unbridgeable gap."
The truth of it settled between them, heavy and suffocating.
The first light of dawn painted the room in pale gold when Senku finally spoke again, his voice raw.
"You asked me once if I'd ever been in love."
She froze. The memory of that night on that damn beach—her depressing question to a ten-year-old boy who'd scoffed at the idea.
Senku's fingers dug into his fists. "I'm in love, (Y/n). With you." The words hung in the air, fragile as the dust motes swirling in the morning light.
Her chest ached. She reached out, brushing his hair back from his forehead—the same way she'd done a hundred times before.
"Senku," she whispered. She pressed on gently, thumb tracing the dark circles under his eyes. "You're not in love with me. You're in love with not being alone anymore."
Senku flinched like she'd struck him. His breath hitched. "You don't know what I feel—"
"I know you confuse comfort for love," she interrupted softly. "Because I did too, when I was a stupid sixteen year old." She smiled, bittersweet, holding his hand up to her face. "One day you'll meet someone who makes your neurons fire in ways no equation can explain. And you'll realize this was just... shelter from the storm."
The pocket watch he always carried ticked loudly in the silence between them.
Senku stared at their joined hands—his now larger than hers—and whispered, "It doesn't hurt any less."
"I know," the girl murmured, pulling him into an embrace.
"I'm sorry," Senku sobbed.
"I know."
April 4th, 2021.
The auditorium hummed with the murmurs of proud families, the scent of fresh flowers and polished wood thick in the air. Senku stood at the podium, his graduation cap slightly askew, the valedictorian medal gleaming against his chest. His voice was steady as he delivered his speech—something about perseverance, about curiosity, about the future—but his eyes kept flickering to the crowd.
And there she was.
(Y/n) sat near the front, her hair now streaked with sun-bleached in random strands from months at sea, her hands clasped tightly in her lap. She didn’t wave or cheer like the other families. She just nodded at him, once, the way she always did when words weren’t necessary. You’ve got this.
Senku’s lips quirked.
Then—movement at the back of the room.
A man slipped in late, his broad frame awkwardly shuffling past knees and purses as he muttered apologies. His hair was streaked with gray, his face lined with exhaustion, but his eyes—sharp, bright, familiar—locked onto Senku instantly.
Senku’s breath caught.
His fingers tightened around the edges of his speech, but he didn’t stumble. He finished with a flourish, the crowd applauding, but all he could think was— He came.
Senku didn’t run. He never ran.
But he damn near sprinted off the stage.
His father caught him in a crushing hug before Senku could even speak, the scent of jet fuel and aftershave flooding his senses.
"Sorry I’m late," his dad murmured, voice rough.
Senku pulled back just enough to glare. "You’re seven years late."
His father laughed, the sound warm and unguarded. "Yeah, yeah. But I’m here now."
The girl lingered a few steps away, hands shoved in her pockets, watching with an expression Senku couldn’t quite place. His father noticed her immediately.
"And you must be (Y/n)," he said, extending a hand. "Senku’s texts about you could fill a novel."
She blinked. "He texts?"
"Against my will," Senku grumbled, but there was no heat in it.
His father’s grip was firm as he shook her hand. "Thank you," he said, quieter now. "For looking after him when I couldn’t."
She shifted uncomfortably. "Someone had to."
Senku’s phone buzzed in his pocket—probably Taiju or Yuzuriha asking where he’d disappeared to—but he ignored it. His father’s phone buzzed too, some NASA alert, and he silenced it with a frustrated sigh.
"Paperwork can wait," he muttered. Then, clapping a hand on Senku’s shoulder: "Let’s get a picture. All three of us."
She opened her mouth—probably to protest, to duck out—but Senku grabbed her wrist and yanked her into frame.
Senku stood between them, his graduation robes slightly rumpled from the sprint offstage. His left arm was slung casually over the girl's shoulders, his fingers giving her sleeve a subtle tug—stay close—even as she pretended to scowl at the contact. His other side was anchored by his father's broad arm draped across his back, the man's calloused hand squeezing his shoulder like he was afraid Senku might vanish if he let go.
"Smile, (Y/n)," he said, grinning. "It won’t kill you."
She stood stiffly at first, arms crossed, but Senku's grip was insistent. She finally relented, leaning into the frame just enough that her temple brushed against his bicep. His father, taller than both of them, bent slightly at the knees to fit into the shot, his free hand giving a thumbs-up to the camera.
And Senku—
Senku was laughing.
Not his usual smirk, not the half-amused exhale he reserved for particularly dumb experiments. This was unrestrained, his head tipped back slightly, his eyes crinkled at the corners, his teeth flashing in a grin so bright it could've powered one of his inventions. The sun caught the gold of his valedictorian medal, the blue of his hair, the warmth of his father's jacket, and the faded navy of (Y/n)'s sleeve where his fingers still clung.
For that single, suspended second, he looked every bit the seventeen-year-old he was—not a genius, not an orphan, just a kid sandwiched between the two people who'd somehow, against all odds, become his family.
The photographer lowered the camera. "Got it."
She immediately ducked out from under Senku's arm, grumbling about "sentimental crap," but not before ruffling his hair with rough affection. His father kept his hand on Senku's shoulder a moment longer, his grip saying what his words couldn't—I'm here. I'm staying.
And Senku, still smiling, reached up to adjust his crooked graduation cap.