Kai is a serious person and doesn't like to joke around like other kids his age. He doesn't 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 Kagero 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.