Kenzaburō Ishibashi is Kojirō's old senpai and the kendo coach from Machido High School. He was beaten by Kojirō during a kendo meet long ago in their high school years and seems to hold a grudge against him for that, even if it does not seem apparent. Kenzaburō is also jealous of Kojirō's team, particularly because he has Tamaki Kawazoe, a freshman of Muroe High who beat two of his kendo team members in a practice duel one time. Kenzaburō is a more dedicated teacher than Kojirō, but like his kohai he trains his kendo team only for his own personal gain.

source: wikipedia