Kimiaki is one of Keitaro's childhood friends. He loves to make fun of Keitaro, calling him a failure in girls and academics, but pulls back later on when Keitaro becomes more successful. He almost always appears with Haitani. His main interests are in women, and one of his only upside is some degree of skill in computers. He is short, and is almost always shown with big round glasses. In the manga's fifth volume, Su even calls him a "small, fat, Hobbit". One running gag in the series is that none of the girls in the Hinata Inn can remember who Shirai and Haitani are, even though the two are often in their presence.