Toshiyuki Karasawa is a second-year high school student of Prefectural Sanada North High School and a member of its student council. A stiff and serious person, Karasawa rarely smiles but he never fails to humor the mischief of his friends. He is a fast thinker who tends to maneuver conversations to his advantage, and has a skill in ventriloquism and giving advice. Still, he is noted to have a crazy side.

He lives next door to Habara and is thus an easy target to the harassment of the Funky High School Girls, but he always has ways to deal with them. Despite his aversion for Habara, he is shown to hang out with her from time to time and lending her some DVDs.