|Japanese Name:||石橋 賢三郎|
|Romanized Name:||Ishibashi Kenzaburō|
|English Name:||Kenzaburō Ishibashi|
|First Appearance:||Episode 1|
|Occupations:||Teacher, Kendo Coach|
|Japanese VA:||Tetsu Inada|
|English VA:||Christopher Sabat|
Kenzaburō is Toraji Ishida’s friend and the kendo coach of two high schools, although the only one named is Machido High school. At the end of the series he marries Toraji's coworker Yoshikawa, who is pregnant with his child.
Insightful and perceptive, Kenzaburō is able to easily perceive someone’s strengths and weaknesses during kendo. He is a dedicated teacher who does his best to help all students, even those from other high schools. While at first it seems that he holds a grudge against Toraji due to losing to him in a match years ago, in reality he simply enjoys the competition. His patience is often tested with his Machido High team due to their antics, but in the end he trusts them to do their best. In the past he admitted that he used to be rather cocky, but after being defeated by Toraji he became more humble and understood the benefits of losing.
In high school he was in the kendo club along with his friend and teammate Toraji. The two often goofed off during school. In a tournament he lost for the first time against Toraji. Ever since then he has been making bets for the trophy, though he does so more out of rivalry than an actual grudge.