Constant Variable (Senku x Reader)

5: Fire the Smoke Signal

Senku's chuckles filled the air as he removed a bunch of charcoals tied together from a bag, placing them down in front of his friends who watched in a mixture of confusion and curiosity.

"We have the three materials we need to make gunpowder." The scientist explained with his trademark smirk as excited grins broke out on the trio's faces.

"We have them already?" Taiju questioned with sparkling brown eyes.

"That's great news!" You beamed with delight. "So, what do we do now?"

Senku began rubbing his hands together in mad glee as evil cackles fell from his lips, looking very much like an insane scientist straight out of a sci-fi movie. "All we need to do now is mix it. It's time for our happy gunpowder cooking session!"

You sweatdropped while Taiju let out an enthusiastic shout of agreement, pumping a fist into the air. Red orbs met (e/c) ones and Senku winked at you, gesturing to the pile of ingredients to make gunpowder. "And this is where you come in as my assistant lab. Are you up for it?"

Your eyes sparkled with determination, showing that you were more than ready. "I won't let you down!"

Senku's eyes softened as he lifted a hand to pat your head, a small smile shaping his lips. "I know."

Your cheeks flushed a light pink and tore your gaze away from him to glance down at your shoes to hide how pleased you felt, your heart thrilling with happiness. "Mn."

With that, the two of you got down to work.

"Ingredient number one for gunpowder..." Senku began his mini-cooking class, holding up one finger as you poured the sulfur into a large bag. "Sulfur, which we can get plenty of at this hot spring."

Both Taiju and Yuzuriha watched the process with rapt attention as the scientist held up another finger. "Number two...Charcoal. We can get all we need by burning wood. (Name), add a few will do. We don't need that much."

Nodding your head, you tossed charcoal after charcoal into the bag, be careful to not spill any of the yellow powder while doing so.

"And number three," Senku lifted the third finger. "the last, but most difficult: potassium nitrate. It'll take a hell of a long time to make this stuff, so...."

He trailed off before whipping out a bag of white powder, winking happily as he held it out in front of Taiju for him to see. "Kukuku! I've already made some to save us time!"

You couldn't help giggling over how cute Senku looked with his act, wanting nothing more than to pinch his cheeks like you would with an adorable five-year-old.

"O-Oh!" Taiju exclaimed in awe before it was replaced by a frown over how familiar the word was. Furrowing his brows, the brunette wrecked his brain and tried to recall where he had heard it from. "I feel like I've heard the word 'nitrate' somewhere..."

A lightbulb went off in his head.

"Nitric acid!" He finally remembered the mini-lecture he received in the cave as Senku explained that nitric acid came from bat poop. "Miracle water! You got it from that cave?"

"You're right for once, simpleton." The scientist replied with an impressive tone while pouring potassium nitrate into the bag filled with the rest of the ingredients needed to make gunpowder. "Ten billion points for you."

After which, he grabbed a stick and began to mix everything all up while the rest of you watched with anticipation. "Potassium nitrate, sulfur, and charcoal all go in the mix, and a pinch of sugar as a secret ingredient gives it a little more oomph. This is glucose that I made from grapes."