Chapter Text
Winter bites harder near the base than it ever did in Ishigami village. Probably due to the trees and such around ishigami village, that the base here is lacking.
The wind cuts through layers like they’re nothing, rattling the half-built frame of the Perseus and sending sharp creaks through the wood. Most of the Kingdom of Science has taken advantage of the lull in construction to rest, to regroup, to not freeze their asses off for once.
Less noise. Fewer people moving around. More time spent near fires, talking, resting, stopping.
Senku doesn’t like it.
Stopping leaves too much room for his brain to wander, and that’s not useful.
So he doesn’t give it any room.
He’s hunched over a makeshift table, notes scattered, charcoal scratching rapidly across paper as he recalculates load distribution for the mast. Again. He already did it. Twice.
Doesn’t matter.
He keeps going.
The first thing Senku notices is that his hands won’t stop shaking.
That, in itself, isn’t unusual. They shake when he hasn’t slept. They shake when he’s been counting too long, when the numbers stack up and won’t settle, when his brain keeps running calculations it doesn’t need to run. They shake when he remembers—
He doesn’t finish that thought.
He pinches his inner arm, hard. The fabric is worn thin from constant use, stained faintly where he’s been… less than careful. It’s fine. It’s always fine.
He flexes his fingers again.
Still shaking.
“Tch.”
It’s probably just exhaustion. Or low blood sugar. Or dehydration. Or—
—or something not important.
He dismisses it.
There’s work to do.
He hasn’t slept in… a while. The thought comes out of nowhere.
Senku pauses, staring at the half-finished notes in front of him.
He hasn’t slept in… 62 hours.
He frowns.
That’s not right.
He pinches the inside of his arm, sharp and quick.
The sting snaps everything back into place.
No—64.
No—he corrects himself instantly, irritation flaring.
64 hours, 13 minutes, 26 seconds… 27 seconds...
He exhales sharply through his nose.
It’s getting harder to keep the count straight. That’s… not good.
The numbers are supposed to be stable. He’s supposed to be able to trust the numbers. Lately, they slip.
“…sixty-four hours,” he finishes, more certain.
Yeah.
That sounds right.
He huffs quietly.
“Yeah, okay. That tracks.”
That would explain the headache.
He rolls his shoulders, trying to work out the stiffness, and goes back to writing.
His hand shakes again.
“…tch.”
Probably just tired.
He adjusts his grip until it steadies and keeps going.
A few minutes later, he stands up to grab another piece of paper and immediately regrets it.
The world tilts hard to the left, his vision tunneling for a second like someone’s dimmed the edges.
Senku stills.
“…whoa.”
He waits it out.
It passes.
Of course it does.
He exhales, rubbing the back of his neck.
“I really need to sleep,” he mutters.
It’s fine.
“Senku!”
He glances up as Chrome jogs over, hands shoved in his sleeves to keep warm.
“You’ve been out here all morning,” Chrome says. “We’re taking a break—come eat.”
“I ate.”
The answer comes easy.
Chrome tilts his head. “When?”
“Earlier.”
“…When earlier?”
Senku pauses.
There’s a blank spot where the answer should be.
He pinches his arm again, harder this time.
Focus.
“…before you came out here,” he says, a little more firmly.
That sounds right.
Probably.
Chrome squints at him.
“…You sure?”
“Yeah.”
Chrome doesn’t look convinced, but he shrugs it off. “Alright. Just—don’t forget, okay? You’ve been going nonstop.”
“I’m aware.”
Chrome grins a little. “Yeah, but like… actually aware.”
“I said I’m aware.”
It comes out sharper than he means it to.
Chrome blinks.
There’s a tiny pause.
“…Okay,” he says, slower. “Didn’t mean anything by it.”
Senku freezes for half a second.
That wasn’t necessary.
He knows that.
Chrome wasn’t pushing.
He doesn’t usually snap like that.
“…sorry.”
He looks away, scratching absently at the bandage on his wrist.
“Just busy,” he mutters.
Chrome studies him for a second longer, then nods. “Yeah. You’re always busy.”
There’s something a little off in his tone now.
Less easy.
“…I’ll leave you to it,” he adds, turning back toward camp.
Senku watches him go this time.
Just for a second.
“…yeah,” he says under his breath.
Then he turns back to his work.
By midday, the headache’s worse.
Not terrible.
Just… there.
Constant.
Like pressure behind his eyes.
He presses his fingers against his temple, thinking.
“…definitely need sleep,” he decides.
That’s all this is.
“Senku-chan.”
Gen’s voice slides in smooth as ever, but there’s something under it. Something careful.
Senku doesn’t look up. “If you’re here to slack off, go bother Chrome.”
“Ouch. Cold.” Gen leans against the table anyway, peering at the notes. “You’ve been at this all morning.”
“I’ve been at this for three days,” Senku corrects flatly.
Gen pauses.
“…Right. That’s kind of my point.”
“I’m efficient.”
“You’re terrifying.”
“Same thing.”
Gen hums, unconvinced. His gaze flicks, brief, subtle, to Senku’s wrist. The bandages are freshly wrapped. Again.
“Chrome's worried about you.”
“I’m fine.”
It comes automatically. Clean. Easy. It’s a lie.
Gen watches him for a beat too long.
“… you sure?” he asks lightly.
“Obviously.”
Another lie.
Senku doesn’t even blink.
Gen smiles, but it doesn’t quite reach his eyes this time. “Well, that’s good. Wouldn’t want our genius scientist keeling over, hm?”
“That’s not happening.”
The words come out sharp and dismissive. Senku turns back to his work.
Gen doesn’t move away.
He shifts slightly instead, leaning more fully against the table, eyes still on Senku
“…You’ve been skipping meals,” Gen says, tone still light, but quieter. “And if I had to guess, you haven’t slept either.”
Senku’s hand pauses for half a second over the page.
Then keeps moving.
“I sleep,” he says flatly.
“Mhm.” Gen tilts his head. “When?”
“Whenever I need to.”
“Which is…?”
Senku exhales slowly through his nose, irritation flickering.
“Gen.”
Still not looking up.
“I’m working.”
“And I’m talking,” Gen replies easily. “Multitasking, remember? You’re usually a fan.”
Senku’s grip tightens on the charcoal, the tip snapping with a soft crack against the paper.
A thin, jagged line cuts across his notes.
“…tch.”
Gen watches that, too.
Watches the way Senku doesn’t immediately fix it.
“…You’re shaking,” Gen adds, softer now.
“I’m cold.”
“Then maybe you should take a break and come sit by the fire with the rest of us,” Gen says, just as quiet.
There’s a beat.
The wind rattles the frame of the Perseus somewhere behind them, wood creaking under pressure.
Senku sets the charcoal down a little harder than necessary.
“I said I’m fine.”
“And I said—”
“I heard you.”
That edge is back. Sharper now.
Gen doesn’t back off though. Not yet.
“…Senku-chan,” he tries again, tone shifting again. “You know I’m not just—”
“I don’t need a babysitter.”
The words come out fast.
Too fast.
They hang there for a second, heavier than anything he’s said so far.
Gen stills.
“…I didn’t say you did.”
“Then stop acting like it.”
Senku finally looks up, eyes narrowed, not angry, exactly, but defensive in a way that doesn’t quite fit him.
“I know what I’m doing.”
Another lie. Or maybe not a lie, he did know what he was doing. He knew that this was unhealthy and unsustainable. He knew that he was pushing away everyone he wanted to stay. Everyone that he wanted to notice something was wrong. He knew that the moment they did notice something and said something, he slammed the door in their faces. He also knew that eventually, if he kept doing this, they would stop trying. He didn’t want that, but he didn’t know how to stop whatever this was.
Gen holds his gaze for a second longer. Long enough to make it clear he doesn’t buy it. Long enough that, for a split second, it looks like he might push again. Senku almost hopes he will.
Then—
He exhales.
The tension slips, just a little.
“Alright,” Gen says, lighter again, like he’s letting it go.
“Have it your way.”
Senku looks away first.
“Always do.”
Gen huffs a quiet, humorless laugh.
“…Yeah,” he murmurs.
He straightens, dusting off his sleeves like nothing happened.
“I’ll stop bugging you.”
A beat.
“Please take a break soon.”
Senku doesn’t respond.
Doesn’t look at him.
Just picks up a new piece of charcoal and keeps writing like nothing happened.
Gen lingers for half a second longer, then turns and walks off.
Senku waits until he’s out of eyeshot before he looks at his hand again. The shaking’s worse. There’s something in his throat, he feels a little bit like he wants to cry.
He doesn’t know why.
“…annoying,” he mutters.
He pinches his arm, sharp.
The sting helps.
A little.
“…just tired.”
That’s all this is.
Has to be.
He keeps working.
He still doesn’t sleep.
Instead, he moves to the lab area as the sun starts to dip.
Probably not his best idea.
He knows that, vaguely, in the back of his mind. Working with chemicals while this tired isn’t ideal. There’s a lot more risks for mistakes and danger. But he’s careful. For the most part.
He’ll be fine.
The solution in the flask bubbles unevenly.
Senku frowns.
That’s… off.
He leans in slightly, trying to figure out what’s wrong.
He knows this process.
He’s done it before.
The answer should be obvious.
It just—
Isn’t.
There’s a weird lag in his thoughts, like trying to remember something just out of reach.
“…c’mon,” he mutters.
Nothing.
He pinches his arm again, sharp.
The sting helps, a little.
Not enough.
He does it again.
“…okay, yeah, that’s—”
He exhales, rubbing his face.
“That’s bad.” Senku mutters.
“Senku!”
A loud booming voice comes from the door way. Sudden enough and loud enough that it causes Senku to jump in surprise.
He turns to see Ryusui standing at the doorway, a large grin on his face. Holding back a sigh at yet another interruption, he turns back to his work.
“Busy.” He knows it’s a hopeless endeavor to get Ryusui to leave him alone but he might as well try.
“Always.” Ryusui grins, too bright, too knowing. “Which is exactly why you should take a break.”
“No.”
“Incorrect answer.”
“Didn’t ask.”
Ryusui steps closer anyway, arms crossed. His gaze is sharper than usual, scanning, assessing.
“You look like hell.”
“Flattering.”
“You’re pale. You’re shaking. And if you tell me you’ve slept recently, I will assume you’re lying.”
Senku clicks his tongue. “Then assume.”
“Gladly.”
There’s a beat.
The wind howls through the lab's frame.
Ryusui’s expression shifts, just slightly. Less teasing. More… serious.
“…What’s going on?”
“Nothing.”
“Senku.”
“I said nothing.”
The edge in his voice is immediate. Defensive. Sharp.
Ryusui doesn’t back off.
“You think I can’t see it? You’re running yourself into the ground.”
“I’m working.”
“You’re self-destructing.”
Silence.
For a second, just a second, something cracks. For just a second, Senku wants to tell him everything. The counting, the nightmares, the pinching, the hyperfocus, all of it. Just for a second…
Then Senku scoffs, turning away. “Dramatic.”
“Realistic.”
“Annoying.”
“Persistent.”
Senku’s jaw tightens.
“Drop it, Ryusui.”
There it is.
The line.
Push further, and it’ll snap.
Ryusui exhales slowly, then lifts his hands in surrender.
“…Fine,” he says, easy again. “For now.”
But his eyes say this isn’t over.
Not even close.
Senku watches as he turns to leave, there’s a strange aching in his chest as he watches Ryusui leave. He doesn’t know why. He pushed him away. The only reason Ryusui’s leaving is because Senku told him to.
He doesn’t get to be upset about that.
He turns back to the solution he’s working on. It’s still wrong.
He can’t figure out what’s wrong with it. He’s too tired to think straight.
The world flickers.
Just for a second. His hearing clips out slightly. Dark presses in at the edges of his vision.
Too close.
Too tight—
Senku jerks back hard, knocking the table.
The flask tips, slips—
shatters on the ground.
He stares at it, breathing a little too fast.
“…okay.”
His voice trembles slightly. He presses a hand to his face.
“Okay, yeah. That’s—sleep.”
Definitely sleep. Not anything else. It’s just sleep deprivation messing with him.
He crouches down and starts cleaning up the spill, a little clumsier than usual.
He gets something on his hand. It stings and will probably itch tomorrow.
He doesn’t really care. He knows he should.
By the time night settles in, the conclusion is pretty obvious.
He’s exhausted. Like, dangerously exhausted.
Shaky hands. Headache. Trouble focusing. Weird half-second lapses.
All signs point to one thing.
“…I really need to sleep,” he says out loud.
Simple.
Straightforward.
Correct.
He just—
Doesn’t.
Because when he tries, he makes it about two minutes before something in his chest tightens, his thoughts going sideways in a way that has nothing to do with being tired.
Too quiet.
Too dark.
Too—
He stands up and goes back to his notebook sitting on the table.
“…nope.”
Not dealing with that.
Not tonight.
So he goes back to work. Because that’s easier. Easier than having to deal with the tightness in his chest and the fog in his brain and shakiness in his hands and—
Sometime deep into the night, he ends up sitting against the wall, notes scattered around him.
His whole body feels off now.
Too hot.
Too cold.
His head pounds in a steady rhythm.
His hands won’t stop shaking.
“…this is what I get,” he mutters.
He leans his head back, just for a second. Just to rest his eyes. Not to sleep.
No sleep.
Just—
Resting.
That’s all.
He wakes up an hour later with a sharp gasp.
Air tears into his lungs like he forgot how to breathe and leaves just as quick.
Heart racing.
Skin drenched in sweat.
And for a second, a terrifying, long second, he doesn’t know where he is.
It’s dark.
Too dark.
Too—
His hand slams against the ground, searching—
Wood.
Cold air.
Firelight in the distance.
Not stone.
Not trapped.
Not—
He forces his breathing to slow.
Counts
1
2
3
4
It steadies.
Senku can feel tears welling up in his eyes. He leans his head back again and squeezes his eyes shut. Taking deep breaths in through his nose and out through his mouth, like how he heard Gen telling others to do.
He just wants to sleep.
He stays there for a second. Just sitting down, trying to get his breathing and emotions under control again.
“…yeah, alright,” he mutters, pushing himself to his feet anyway.
“I’ll sleep later.”
He doesn’t tell anyone.
He's just tired.
Like that explains it.
Like that makes it manageable.
He doesn’t go back to sleep.
By morning—
He can barely stand.
He knows something’s wrong.
Knows it clearly.
He just doesn’t care.