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The Stone World had its fair share of inconveniences, but for you, the biggest one had been discovered almost immediately. The first time you spent an entire afternoon under the sun, helping Kohaku gather food near the river, your skin had turned an angry shade of red.
It was ridiculous, really. The others had laughed, assuming it was a temporary reaction. But by the next morning your shoulders ached, your cheeks stung, and you could barely move your arms without feeling like your skin was being set on fire.
It hadn’t taken Senku long to realize what was happening.
“You’re a redhead,” he’d mused, watching you wince as Kohaku helped apply wet cloths to your burned skin. “And not just that—pale skin, American origin… You don’t have the melanin to handle this kind of prolonged UV exposure.”
Kohaku had tilted her head. “Melanin?”
“Basically, her skin is really bad at handling sunlight. People with darker pigmentation have natural protection, but she’s the kind of person who would have had sunscreen in the old world,” Senku explained, arms crossed as he analyzed you like a particularly interesting science experiment.
You had groaned, half-exasperated and half in pain. “And, let me guess, there’s no sunscreen in the Stone World?”
“Obviously not.”
That was three days ago. Since then, Senku had gone strangely quiet on the matter, which meant one of two things: either he didn’t think sunscreen was possible, or he was busy figuring out how to make it himself.
And knowing Senku Ishigami, it was probably the latter.
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You sigh, watching the sun hover high in the sky as you sit under the shade of a large tree near the village. Kohaku had flat-out refused to let you work again until the burn healed, and while you appreciated the concern, you couldn’t shake the uselessness weighing on your shoulders.
“Getting restless?”
Senku’s voice pulls you from your thoughts, and you look up to see him standing over you, his usual smug grin in place. His makeshift clothing flutters slightly in the breeze, and he’s holding a wooden bowl filled with a strange, pale paste.
You raise an eyebrow. “What is that?”
“Your new best friend,” he says, crouching in front of you. “Took me a few days to work out the formula, but I think this’ll do the trick.”
Your eyes widen. “Wait—no way. Is that… sunscreen?”
“Damn right it is.”
Your heart leaps. “Senku, that’s amazing!”
He chuckles, pulling off his bandage-sleeves. “Of course it is. Science is amazing.” Then, without warning, he dips two fingers into the mixture and reaches for your arm.
You flinch instinctively. “Hey—wait, what are you—”
“Relax,” he says, rolling his eyes. “You’re just gonna make a mess if you do this yourself.”
You huff but don’t argue as he starts applying the homemade sunscreen to your arms. The paste is cool against your still-healing skin, and you let out an involuntary sigh of relief.
Senku smirks. “Feels good, huh?”
“Yeah,” you admit, cheeks warming. “What’s in this stuff, anyway?”
“Zinc oxide, primarily. It’s one of the most effective UV blockers. I had to make it by roasting zinc ore until it oxidized—pain in the ass, by the way—but once I had that, it was just a matter of mixing it with some animal fat and plant oils for consistency.”
You blink, impressed. “You figured all that out in three days?”
“Tch. If I had the proper equipment, I’d have done it in three hours.”
You laugh, watching as he carefully spreads the mixture over your skin. Despite his usual cocky attitude, his touch is surprisingly gentle. He works with quiet precision, ensuring every inch of exposed skin is covered.
It’s… nice.
The realization hits you like a stone to the head. Senku is always so focused on science, so analytical, that it’s easy to forget he’s also incredibly thoughtful in his own way. He hadn’t just made sunscreen because it was an interesting challenge—he’d done it for you.
Your gaze softens. “Thanks, Senku. Seriously.”
He pauses for half a second before smirking. “Don’t mention it. Can’t have you turning into a boiled lobster every time you step outside.”
You groan. “Oh my god, I will actually push you into the river.”
Senku chuckles, clearly pleased with himself. “Not before I finish applying this.”
He moves on to your shoulders, rubbing the sunscreen in slow, even motions. The casual intimacy of it makes your face heat up, and you pointedly look away, hoping he doesn’t notice.
“By the way,” he says, breaking the silence, “this isn’t a one-time fix. You’ll have to reapply it regularly, especially after swimming or sweating too much.”
You nod. “Got it.”
“And you still need to stay in the shade when you can. This isn’t as strong as modern sunscreen, so don’t go getting cocky.”
You smirk. “Me? Cocky? I think you’re projecting.”
He snorts. “Says the girl who thought she could work all day in the sun without consequences.”
You glare at him playfully, and he just grins in return. The warmth in your chest spreads.
After a few more minutes, he finishes applying the sunscreen and sits back, wiping his hands on a cloth. “Alright. That should do it.”
You stretch your arms, already feeling better now that your skin isn’t exposed and burning. “You’re a lifesaver.”
“No, I’m a scientist,” he corrects. “There’s a difference.”
You roll your eyes, but you can’t stop the smile that tugs at your lips.
Just then, Kohaku appears, arms crossed. “Are you two done with whatever weird thing this is?”
You blink. “It’s not weird, it’s science.”
She squints. “Sure. Science.”
You glance at Senku, who just smirks knowingly, and suddenly, you’re very aware of how close the two of you had been moments ago.
Kohaku raises an eyebrow. “Well, whatever. If you’re feeling better, you can come help me now.”
You glance at Senku. He shrugs. “You should be fine for a while. Just don’t roll around in the dirt too much.”
You huff. “I’ll try to restrain myself.”
As you follow Kohaku, you steal one last glance at Senku. He’s already moved on to another project, but there’s a tiny, almost imperceptible smile on his lips.
Your heart does a little flip.
Yeah. Maybe the Stone World wasn’t so bad after all.