His relationship with Kai, at first was rocky. They didn't get along too well though they learned to enjoy each other company. Kai is quite supportive of Aichi though only when Aichi learned how to do things by himself and become more confident. Aichi taught Kai how to have fun in Cardfight again when Kai forgotten how much fun he was having before his change in school and his parent's death. During Season Two, Kai was withdraw from him since Aichi needed to learn how to do things by himselves and to not count on others to help him. In Season Three, Kai noticed how much Aichi has changed. He was happy and sad at the same time though he was glad to see Aichi being himself now. However, this now puts him in a role reversal as, through observing Aichi and Ren's strenghts through their cardfight, he feels as though they have exceeded him by leaps and bounds. Tempted by the promise of strength, he willingly takes the power of Reverse and the Link Joker clan so he can face Aichi one on one as his equal. Aichi, realizing the danger of having such strength using a dark power, resolves to personally defeat him and release him from Reverse.