One of the main protagonists, and a powerful Vanguard player. Before the start of the series, he gave Aichi Blaster Blade in the hopes of battling him in the future. After losing to Aichi, he concluded that he would probably be worth battling in the future, but that he was still weak and would not improve quickly. Kai only likes battling strong players who have the skill to back up their talk and hates weak players who talk big. When Kai plays, he adds "the" whenever he declares a move (examples - "Stand up! THE Vanguard!" and "Check THE Drive Trigger!"). He battles with a Kagero Deck that is based on Dragons, and his ace is Dragonic Overlord.
Toshiki, Kai- Before the beginning of the show, it was stated that Kai was drawn to the emotionally distraught and physically beaten down Aichi. It was in an act of kindness that Kai gave to him a Vanguard card said to embody the spirit of a powerful warrior, who would help him become strong one day, the Blaster Blade. Aichi, took the card and through the years of his life, was tormented and picked on. Yet, he still kept up his faith all because of the card that was given to him, in hopes that one day, he would be able to show his true strength to the world. ~