Chapter Text
In the bustling science club room, the air vibrated with the clink of test tubes, the hiss and splash of chemical reactions, and the excited chatter of students immersed in experiments.
"Look what I found!" Y/n announced, proudly displaying a clear plastic bug container. His hands trembled with anticipation, careful not to disturb the tiny creature inside, while his face lit up like a kid on Christmas. "It’s a citrus longhorn beetle. I discovered it under the tree in my backyard." He explained eagerly, eyes sparkling as Senku’s gaze shifted from the container to Y/n, already bracing for his usual scientific critique.
"Did you know these are some of the bugs you can catch in Animal Crossing: New Horizons? Just like in real life, they’re found on trees or stumps. These guys,” Y/n placed the container on the work table between them, "are invasive insects. Their larvae bore into hardwood trees, feeding on the wood and creating entry points for fungi and pests that can devastate the trees’ nutrients and cause them to wither." His hands animatedly mimic the thrill of discovery.
Senku’s eyes lingered on the bug a moment longer before flicking back to Y/n, a playful smile tugging at his lips. "Not bad, cricket. So, I assume this little guy will be your prized pin on your collection?"
"Absolutely! I’m planning on getting some more pins on the way home—I’ve been running low for ages," Y/n said, fists clenched in eager anticipation.
Suddenly, a loud noise shattered their focus, and the door snapped open with a dramatic slide. Everyone jumped in surprise. Y/n’s shoulders stiffened slightly as he glanced over Senku’s shoulder toward the door.
“This is it, guys!” Taiju’s booming voice rang out as he stormed into the room, eyes alight with excitement.
"My mind's made up—I’m finally going to tell her how I feel after five long years!" Taiju declared, practically bouncing with energy.
“Good for you," Y/n said with a subtle thumbs-up. Senku shot a quick, unimpressed glance at Taiju but showed no other reaction.
“Wow, fascinating. Sorry I can’t leave the lab right now," his tone was flat and dry. “But I promise to cheer you on so loudly that my vocal cords might give out!" With that, he turned back to his project.
“Awesome!" Taiju exclaimed, beaming. "You guys are the best!”
“No you big oaf," Senku said dismissively, sticking his finger in his ear. "I won’t project my voice for your cause, not even a little." Y/n chuckled at the scene.
"Come on, man!” Taiju groaned loudly.
"Well," Y/n tilted his head, “you’ve felt this way for how long? And now, finally, you’re gonna say something?” He adjusted his glasses, teasing.
“Exactly. I can’t support your illogical behaviour, but I can give you something logical as hell,” Senku said smoothly, grabbing a small vial of clear liquid from beside a machine. Holding it up with his glove, he grinned devilishly. “I developed this love potion—it maximizes your pheromone levels, giving you a ten billion percent chance of winning her over.”
Y/n resting his chin on his hand watched with mild amusement as Taiju looked at the vial, furrowing his brows. Then, with a determined stride, Taiju poured the liquid down the drain.
“Thanks, but no thanks, Senku,” he said firmly, returning the empty vial. “I’ve got to do this myself." He strode out the door with purpose, leaving it to close behind him.
Silence settled thickly in the room, everyone exchanging surprised glances.
“Good for him,” Y/n said casually, leaning back.
“Whoa, you made a love potion?” a boy with brown hair asked curiously, eyes fixed on the sink.
"Use your brain," Senku replied, tossing a lit match into the sink and igniting it. Flames erupted, prompting a wave of shocked reactions. "It’s gasoline—refined from plastic bottle caps. Polyethylene’s molecular structure is akin to a long hydrocarbon chain—minus a few hydrocarbons. You can tell by just looking at it."
“Well, I can’t," sighed the boy, rubbing his head, as murmurs of agreement spread.
“Yeah, but” another boy interrupted, “if Taiju drank that, wouldn’t it have killed him?”
Senku chuckled, eyes twinkling. "No, the odds of him actually drinking it were ten billion to one. He’s dumb but he’s too straitlaced.” Y/n nodded in confirmation.
Suddenly, outside, Taiju’s voice boomed: "Yuzuriha! Sorry, I’m late!" This drew some kids to the window, watching the scene unfold.
“A hundred yen on heartbreak," one muttered.
“Three hundred on her making him cry," another offered.
“Five hundred on her calling him a creep," a third added.
Senku smirked as he cracked open a tall black energy drink. “I bet ten thousand she’s into him too.” The others stared in shock.
"Really?" they asked together.
"Yuzuriha’s not that type," Y/n mused, taking the can from Senku and taking a sip. His face twisted at the bitter taste, so he handed it back. “Why do you only drink the original Monster flavour? It’s disgusting."
“You’re the one who sampled it without asking," Senku said, finally sipping his own. His eyes suddenly widened as a bright green light appeared on the horizon, fierce and ominous. Senku’s brow furrowed, and he let out a small gasp.
“What the hell is that?” Y/n stammered.
Then everything went black—a void of silence, of sensation. Only Y/n’s thoughts remained.
Days, weeks, months, years, decades passed in endless stillness.
God, how long has it been? I should’ve kept track, but I’ve waited too long to start. It’s probably all wrong now.
The most logical thing is, that’s probably what Senku’s doing. The smartest—yet most insane—thing I could imagine.
Millennia drift by.
I wish this—whatever this is, a coma? Doesn’t matter, actually killed me. Being aware but nonexistent is pure torture. All I ever wanted was to make art, collect bugs, and talk about animals.
I hope my cats are okay.
I like my own company mostly, but this is beyond cruel.
I miss my friends.
I miss sharing my interests.
I miss everything.
CRACK.
The sound of cracking stone was deafening compared to the void. Y/n felt the fragments flaking off from outside, and suddenly his capsule shattered. He stumbled back, eyes narrowing as blinding sunlight flooded in, revealing a lush forest.
"Figured it’d work on you," Senku’s voice echoed.
Y/n’s eyes widened briefly, then squinted, as Senku’s figure blurred in the distance.
"Okay, I have a ton of questions," Y/n said, shivering from the breeze and instinctively covering himself. Of course, he was naked. "But more than anything, I’m just glad to see you."
"It’s June 3rd, 5738. Not your usual sleeping-in, huh, Cricket?" Senku grinned, sparking more questions in Y/n but knowing he’d find out everything soon.
"I knew you’d keep track of time. So, it’s just us now, and humanity’s hit a hard reset. That’s why it’s just…" Y/n gestured vaguely at the surrounding wilderness.
"The short version, yes. Taiju’s still stuck in stone," Senku replied, starting to walk away, beckoning Y/n to follow.
"Honestly, I’m terrible in survival situations. I’m not built for this," Y/n groaned, walking a bit behind, eyes on the blurry ground.
"Your zoology and entomology skills are ten billion percent valuable in this Stone Age,” Senku said with a smirk.
"Yeah, but what good’s that if I can’t see two feet in front of you, and have the health durability of a Victorian child with the plague?” Y/n frowned, narrowly avoiding a rock.
"You’re near-sighted, but we’ll make it work. More help means faster progress—and glasses for you," Senku said, stopping at a clearing. Y/n caught his breath, taking in their new home with awe.
"I can’t believe you managed all this alone," Y/n said softly.
"We’ve got work to do if we’re going to catch up with science—and even surpass it," Senku said with fierce determination. "This is just the beginning. Get excited." Y/n smiled, sharing his enthusiasm.
He glanced at Senku’s poorly stitched clothing. "Have I taught you nothing?" he teased, a disappointed sigh escaping. "A blind drunk could stitch better than this.” Y/n clicks his tongue in disapproval. “At least tell me you have some hide and bones, I'd like to make my own clothes," Y/n added, grabbing some brittle remains and getting to work.
Months passed, and all in all, the two made some decent progress especially with the two's shortcomings. Y/n successfully made himself clothes, patchy as hell but given everything it was great. It was a beige one-piece made out of hide, over the top was a dark brown hooded cloak, made from animal skin that Y/n managed to catch in some crudely-made traps by the base.
This day Senku left the base, heading towards the cave where Taiju’s stone body was placed.
Y/n was by the edges of the clearing around the home base, a woven basket in his hand, while the other was carefully inspecting the local flora. Crouching by the bushes to examine it, given how long it’s been it would be harder to tell which ones were saved for use, even more so with Y/n being visually impaired.
His fingers held a clutch of berries from the bush, his brain deciding what species of plant it was.
“SENKU YOU’RE ALIVE TOO?!” A loud booming voice echoed through the forest, causing flocks of birds to fly off. Y/n’s hand flinched, causing him to crush the berries in his hands. The dark liquid stained his hand, and he dropped the crushed berries on the forest floor, wiping the juice on the bottom of his shorts.
“Looks like someone finally woke up.” He chuckled to himself. Adjusting his hold on the half-filled basket, he walks over to the main part of the camp. However, once he arrived, he barely managed to place the basket down before getting pulled into a tight embrace from the man of the hour.
“Y/n it's so good to see you!” Taiju exclaims, squeezing impossibly tighter around Y/n. He lets out a sound, halfway between a squeak and a sigh.
“Good to see you too, you big puppy.” Y/n’s words were muffled by the embrace, awkwardly patting his bare back.
“Keep hugging him like that, and you'll crack his ribs. And we're not exactly in a position to perform emergency surgery.” Senku smirks, sticking his pinky in his ear. Taiju pulled back, letting go of Y/n.
“Right! Sorry Y/n.” Tajiu rubs the back of his head.
“It's fine,” Y/n smiled, straightening out his clothes. He almost forgot how much he missed this, The only one left to complete this group was Yuzuihra. “Glad you're finally here, man. Now that we have someone with brawn, surviving will be so much easier.”
—-
A day has passed since the newest member of civilization joined. It made everything feel a bit lighter with Taiju around, literally and figuratively. It made it feel less like everyone was only in survival mode, it helped that Taiju kept heading out to forage for food.
Taiju placed down a huge basket, the thing was practically overflowing with herbs, mushrooms and the occasional small animal.
“That's definitely a plus-sized haul, Taiju.” Senku’s eyes flicked up at Taiju. “You have a real-life cheat code for stamina?”
Y/n dragged over two smaller baskets, placing them right by the larger basket. He began to sort them out. He held out a handful of small white mushrooms, with an almost fuzzy texture.
“This is toxic,” He tossed the pile into the basket, he grabbed a bundle of brown capped mushrooms, tossed them into the other basket. “Safe,” Then he pulls out a red and white mushroom, immediately tossing it into the first basket.
“If it looks straight out of a Mario game, pass it up,” Senku added looking over at Taiju.
His eyes widened as he held up a green herb, Y/n grins. “Awesome, mugwort. It's safe and has medical properties.” he places it in the other basket. “Do you remember where you found this?” Y/n looked up at Taiju.
“Oh, that? I think I found it pretty close to camp, still a trek away though.” Taiju beams. “I can grab more if it's that useful.” He smiled.
“Yeah, that'd be great. Thanks Taiju.” He smiled back.
“On it! I'll also check in the other direction, be right back guys!” Taiju picked up the large, now-empty, basket. Dashing away into the forest. With his departure, the camp was silent once more, Y/n placing the last herbs in the basket.
“Come on,” Senku looked over at Y/n, motioning him over to the direction Taiju had just headed towards. “Someone’s gotta explain the big oaf about the fluid.”
He sighed, getting up and stretching a bit. “Alright then, lead the way.” Y/n’s hands instinctively reached to push his glasses up, pausing remembering the absence of his glasses. His brows furrowed briefly, his hand falling to his side, and he walked behind Senku.
“You'll get your glasses back soon enough,” Senku shrugs, looking forward. Slowing his step as the terrain got more difficult to navigate, accounting for the other’s blindness.
“I mean,” He started, pausing to step over a big tree root, “If anyone could do it, it would be you, Senku.” He smiled, trying to pick up the paste. Finally, the two arrive at the entrance of the cave,
“WOAH, ME AND SENKU HAVEN’T BEEN HERE YET, SO THAT MEANS SOMEONE ELSE SURVIVED.” Taiju’s voice echoed from inside.
“It was me, idiot.” Senku boredly said, sticking his pinky in his ear. Taiju whipped his head around, looking over his shoulder.
“HUH? NO WAY.” Taiju continued to yell, even though Senku and Y/n were both walking closer to him. His shoulders slumped a bit as the two stood next to him.
“Are we the only ones left, for real? Like the last humans still alive?”
“That we know of, yeah.” Y/n patted Taiju on the back, a weak attempt at comfort.
“We’ll get more. That’s a top priority,” Senku glanced longways at Taiju and Y/n. “I mean, the three of us alone, just a couple of dudes. Can’t ‘restart humanity’ if you catch my drift.”
“Yeah that’s true,” Taiju’s eyes widened at Senku, apparently this one didn’t go over his head.
Partly true, but, there’s always me. Since I woke up I’ve lost the resource to take testosterone, five months now to be exact. It’s only a matter of time before my body fully processes the fact. Senku already knew of this fact. Taiju obviously doesn't know, but not because I don't trust him or anything. I just would rather not have a serious and awkward conversation like that if I can help it.
“Cricket.” Senku’s voice interrupted Y/n’s thoughts. He blinks a bit, his eyes acknowledge the fact that Senku is standing in front of him now.
“Sorry, what’s happening now?” Y/n tilts his head to the side.
“We're heading back to camp, come on.” Senku pointed his head towards the outside of the cave. Y/n nodded, walking behind Senku and now Taiju, who was waiting for them.
Once the three arrived back at camp, Senku had placed a stone sparrow on a tree stump, holding the clay jar full of the fluid in his other hand. Taiju and Y/n stood around, watching Senku.
“Let me guess, you pour some of the miracle stuff on it, the stone breaks and the bird wakes up.” Taiju leaned forward, his hands on his knees. Senku poured the yellow liquid onto the stone bird.
“I wish it were as straightforward as that, it would rule.” Senku sighed, watching as the liquid had no affect whatsoever on the sparrow. The three sighed in disappointment.
“I've been working like a madman on this project, using every last method I could think of,” Senku walks to the shed, which has shelves and shelves of stone sparrows. “It's like something from a fantasy world, is it all mineral?” Senku placed the stone bird with the others. “Are there living cells underneath?”
“So what you're saying is, there are even things that science can't explain.” Taiju’s brows furrowed. This caused a chuckle to bubble out of Senku’s chest.
“There we go, that tired old cliche,” He looked back at the two behind him, “truth is, it never quite stands up to the scientific method. Science is often a slow process.” Senku paused, “Some liquor might speed things up.”
“Didn't peg you for the drinker type,” Y/n teased, crossing his arms.
“Not exactly,” Senku smirked, putting his hands on his hips. “If we mix it with the nitric acid, it would make nital, which is an industrial-strength etching agent.”
“What did you say we needed?” Taiju interjected.
“Huh? I said we could make nital. It gets into the ferrite grain boundary and—”
“No! Don't confuse me with some kinda ‘science talk.’ I mean the part about liquor,” Taiju then reached out behind him, pulling out two bundles of grapes from the basket. Holding it out towards Senku. Y/n’s eyes widened as he looked over at Senku.
“Wine comes from grapes, yeah? And that is a type of alcohol, isn't it?” Senku’s eyes widened before a grin formed on his face, looking up at Taiju.
“Way to go Taiju!” Y/n hits Taiju’s back, giving him a thumbs up.
“Not bad you big oaf.”
Weeks have passed, and the first batch of wine has finished. The trio are up in the hut, sitting on the floor. Taiju pours out the wine into a small clay container, while Senku swirls the wine he poured for himself in a clay wine. Y/n leans back against the wooden hut walls.
“Thought of something underage drinking’s a crime too.” Taiju placed the now-empty clay container next to him, looking over at Senku, who seemed to be laughing at this.
“Not a problem, we're all over thirty-seven hundred years old,” He holds up the clay wine cup in the air.
“Not like there's anyone to enforce those rules anyway,” Y/n shrugs, a small grin on his face.
“That's right,” Taiju laughed, before pressing the giant clay container to his lips, taking a swig of the wine, and half of it dribbled down his chin. Then his face scrunched up, turning his head to the side as he spat out the wine. Senku took a small sip from his own cup, while Taiju hacked up a lung next to him.
“Hm, not bad. Turned out way better than expected. But it's ten billion times worse than what was on the market, though.” Senku handed over the cup to Y/n, “Try it.”
Y/n takes the cup from Senku, taking a sip. His brows furrowed as he placed the cup between himself and Senku. “I've never liked the taste of wine, and this doesn't help.” He sighed.
“That was so easy, just stomping grapes and waiting around?” Taiju murmured.
“One step at a time, my friend,” Senku rests his forehead on the palm of his hand, “Though I hate to say it, our paste will slow down.” Senku cracked his neck. “This'll be a course in distilling wine for dummies. Our goal is to acquire some brandy.”