Yotasuke Takahashi, also known as Sekai-kun (セカイくん), by Haruka Hashida, is a former member of the Art cram school that Yatora Yaguchi attended, and is currently a second-year university school student at Geidai, Tokyo University of the Arts.

Yotasuke has a reserved and shy personality, but it is also shown to be standoffish and easy to anger. He’s blunt, and often says things as they are in his mind without stopping to explain to others what he means. He is completely aware of the height of his artistic abilities and isn't afraid to admit it. Though, he regards his skill as something he is not actually confident about, and states that it is simply a fact that he makes good art.