|Manga Debut||Chapter 1|
Kōsuke (コースケ, Kōsuke) is a first year student of Nangokuren High School. He is friends with Rintaro and Tamao, as well as a member of the ""AKB"" (Brotherhood of Virginity) along with his two friends.
Kousuke is an average teen, with light color hair with long sideburns and thin eyebrows. He wears a red jacket with a black trim, over a white button down shirt that that is kept unbotton at the top and not tucked in, a black tie with two yellow lines, a belt, black pants, and black shoes.
Kousuke is shown to be perverted, like his friend Tamao. He has also shown to care about Rintaro because he became friends with him and even protected Rintaro when he was going to be ambushed.
First Encounter with Rintaro
Kōsuke joined the class in a swimming pool. After the class however, Tamao became a suspect by both Keiko and Makoto for stealing Ayane's underwear, which he stated that he didn't do so. Both he and Kosuke seek Rintaro and inform him that they are innocent, while requested Rintaro to clear their name by find the real culprit who stole the underwear. While seemly relief that their sworn brother is eager to help them, Kōsuke went speechless as he deemed Rintaro as a wannabe detective. After Rintaro began to investigate, Tamao and Kosuke attempts to flee before they are warped by the girls which they claimed that their suspicions remains.