S1·E26 Beginning of the Storm! National Convention!!

Team Q4 arrives at the site of the national tournament grounds and meets Team Caesar, composed of Kenji "Koutei" Matsusada and the siblings Gai and Yuri Usui, who were the last national tournament's finalists and previous winners. Everything seems to be going well, but due to Kai's increasingly arrogant and insulting attitude, Kamui decides he can no longer work with him and abandons the team. Aichi attempts to go after him, but is reminded that if he also leaves, Team Q4 will be unable to participate in the tournament and will therefore be disqualified. With some advice from Kenji, Aichi decides to win the preliminary rounds and earn Q4 a spot in the finals, so Kamui can return.