Kai is a serious person and doesnt like to joke around like other kids his age. He doesnt talk much or to anyone. When cardfighting he is shown to be more serious and confident on winning the game without any need of support. Despite his selective mute personality he has a best friend is Taishi Miwa. Toshiki Kai main deck focus is the Kager clan deck. His trump card is Dragonic Overlord. His strongest and most commonly used cards are normally Flame Dragons. In season 2 Kai main deck focus is the Narukami clan deck. Kai stays with this clan in Season 3 although hasnt given up on his Kagero deck. After seeing how far Aichi has come Kai now doubts his own strength in comparison and seems to be striving to prove that hes able to keep up.