Kachiro Kato (加藤 勝郎 Katō Kachirō) hangs around a lot with Satoshi Horio and Katsuo Mizuno. Although he is not very good at tennis he thoroughly supports the team. He has a father who coaches at an expensive tennis club. Though he is normally polite and meek, Kachiro believes strongly in justice and fights to the end to defend his beliefs.