Koudan Kaikan is an enormous international karate dojo/gym in Ikebukuro. Koudan Kaikan was originally intended to be an extension of Kaburagi Karate. The director during this time was Kaburagi Juuzou. But during events unexplained, Izumi Koushou (pupil of Kaburagi Juuzou, and kouhai of Tachibana) kicked both out and Kaburagi-ryu was forcebly split from Koudan Kaikan. Koudan Kaikan is sponsered by K.O.S. (King Of Strikers), which is one the biggest martial arts series around the world and it holds one of the biggest martial arts tournament around the world. Beacuse of this amazing sponsor, Koudan Kaikan is one of the biggest karate dojos in the manga (they have the most karate dojos around the world). Their gym can afford state of the art facilities and they have well-known fighters/trainers that represent Koudan Kaikan as well.