Constant Variable (Senku x Reader)

7: Where Two Million Years Have Gone

"Yeah," Kohaku confirmed, blue eyes glowing with excitement. "I'm sure they'll be dependable allies. I know one man who'd be perfect. Allow me to guide you, Senku. Come with me."

There was a moment of silence as Senku contemplated her words, his gaze sliding over to your sleeping figure – facial expression relaxed and dreaming on peacefully with a contented smile, oblivious to the conversation happening between both of them.

Then, he replied in a soft voice. "Alright. We'll come with you."

Time skipped

"Hot water?" Senku raised a brow in question as he watched Kohaku fill a large jar with water from a hot spring, wondering what she would need it for.

"Yeah." Said blonde calmly answered, her focus trained on the task at hand while she gave an explanation. "I take it home to make a hot spring bath. For healing purposes."

The scientist's eyes widened in amazement as Kohaku carried the heavy jar with ease, a small contented smile on her face. Blinking his eyes once, then twice, he commented. "You look like a ten billion percent healthy kid to me. What use does a lively lioness like you have with any more healing?"

"I'm not a lioness!" Kohaku protested, her brows furrowing in irritation. "And it's not for me! It's for my sister!"

You let out a yawn, still feeling slightly sleepy from having woken up so early this morning as tears gathered in the corners of your eyes. Rubbing away your eyes, you asked, "Why do your sister need it for? Is she sick or something?"

Turning her back to the two of you, Kohaku let out a helpless sigh as she replied, "Honestly...She's such a troublesome nuisance of an older sister. She's been especially sick lately. If only I could swap her body with my exceedingly healthy one..."

She trailed off and began to walk off, not bothering to wait for a response from either of you. You didn't have to see her facial expression to know how worried she was for her sister because you could hear it clearly in her voice.

Both you and Senku exchanged gazes before the scientist simply shrugged and turned to follow after their new friend. You furrowed your brows in slight confusion at Senku's lack of response, but before you could mull over it, you noticed the lack of striking green hair and hurried off in the direction Senku had gone lest you got left behind.

You almost tripped over your feet, but thankfully didn't fall when you caught up to the teen and fell into step beside him.

Red orbs narrowed slightly, fixated onto the jar that Kohaku was still carrying without so much as breaking a single sweat. "That jar looks like a little less than fifty litres. It's not quite enough for a bath. How many trips do you make with that heavy-ass jar? Every single day..."

You remained silent as your gaze jumped back and forth between the scientist and the blonde who let out a scoff before answering, "It's just part of my daily training. I'm a lot stronger thanks to it, too. I should be grateful to my nuisance sis—"

Her sentence got cut off when suddenly, her legs gave in and Kohaku stumbled, nearly spilling the large jar of hot water if it wasn't for Senku who stopped the jar from tipping over with just one hand.

"You haven't fully recovered yet, have you?" The scientist questioned with a smug smirk. "I can't have you overexerting yourself and dying on me. Hand it over."

"Senku..." Kohaku breathed out in awe.

On the other hand, you weren't sure if Senku's suggestion was a good idea when you remembered all those times where he struggled with heavy labour due to his lack of strength and short stamina.