Senku chuckled at Tidus' incredulousness. "There's nothing wrong with Kinro's spear." He grinned. "Paper with the combination of inflexible plastic yields carbon fiber reinforced polymers. Lightweight but incredibly strong, they used that kind of thing in race cars and rocket ships."

He brightened at Roland's question. It was less about being called a wunderkind, which he couldn't refute, although he could certainly try, and more about answering how he made plastic.

"Glad you asked! We made what was humanity's first plastic, phenol resin. First, you steam wood to get tree oil, boil it and add it to piping hot copper and it gives you formalin." Senku offered a grin. "That's a chemical they use to preserve bodies. You might know it as formaldehyde, but that is specifically the gas compound, when it's distilled into water, it's formalin."

"Anyway! Then you take the cinders from burning coal, add a little sodium hydroxide and the formalin and you get phenol resin!"