OVA
Description
Kachirō Katō is a first-year student at Seishun Academy (Seigaku) and a friend and supporter of Ryoma Echizen. He is generally recognized by his neat bob-style haircut and his small, youthful appearance. Physically, his height is listed as 148 centimeters, he weighs 53 kilograms, and he is right-handed. His birthday falls on March 2nd.

In terms of personality, Kachirō is normally polite, quiet, gentle, and somewhat timid. This reserved nature can make him an easy target for more aggressive individuals, and he has been physically assaulted by the volatile player Jin Akutsu. However, beneath his meek exterior lies a strong belief in justice. He has proven to be brave and stubborn when a situation calls for it, fighting to the end to defend what he believes is right. Although he is not a highly skilled player, he is a thorough supporter of the Seigaku team and can often be seen cheering for his teammates at matches.

His motivations are largely centered on supporting the team, particularly his friend Ryoma Echizen. He actively assists by gathering intelligence and scouting future opponents, sometimes putting himself at risk in the process. He is also motivated by a sense of justice, as shown when he challenged a second-year named Masashi Arai who claimed that injuries to the regulars gave him an unfair chance to become a starter. Despite being outclassed, Kachirō persisted in the match, even though losing would mean he had to quit the club.

Kachirō's role in the story is that of a supportive friend and an underdog who demonstrates quiet determination. He is part of a trio of first-year students alongside his close friends, Satoshi Horio and Katsuo Mizuno. His family background includes a father who works as a coach at a tennis club. During one incident, his father was verbally abused by a man named Sasabe, who taunted him for not becoming a professional tennis player due to an injury. Kachirō was helpless to assist his father but was relieved when Ryoma Echizen stepped in and humiliated Sasabe.

His key relationships are with his fellow first-year students, with whom he is usually seen, and with Ryoma Echizen, whom he loyally supports from behind the scenes. He also has connections with upperclassmen; during his challenge match against Masashi Arai, Kachirō gained a new respect for him upon discovering that Arai had been playing with ankle weights on, a handicap that made their match more equal.

In terms of development, Kachirō shows growth in courage and resilience. He begins as a timid boy but finds the inner strength to stand up to older, more powerful students. His character demonstrates that belief and persistence can be as significant as raw talent. Regarding notable abilities, he is not depicted as a tennis prodigy like his friend Ryoma. His primary contributions are his information-gathering skills, his loyalty, and his stubborn persistence on the court, even when facing a superior opponent.