Toshiki Kai is the deuteragonist in the Cardfight!! Vanguard (V Series Anime), and has recently enrolled as a first year at Hitsue High School since he moved back to his home town. He seeks to gain true strength when it comes cardfighting. His Vanguard Circle is red.
Despite being continuously referenced as 'Kai' both in-series and out, Kai's given name is in fact Toshiki. Going with Japanese rules of etiquette, none of the characters in Vanguard refer to Kai by his given name because none of them are close enough to him socially to speak to him as such. Even his best friend Taishi Miwa likely calls Kai by his surname due to them respecting one another.
His family name, Kai (櫂) means paddle; oar; scull.
Kai is a serious person and doesn't like to joke around like other people 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 selectively mute personality, he has a best friend, who is Miwa. However, after his cardfight with Aichi, he is more social and nicer than his original series counterpart.
Kai is normally seen wearing his Hitsue High School uniform, which consists of a blue jacket and pants with white trim, and a white dress shirt. His uniform, however, seems a bit worn out.
His casual attire consists of a tan, zip-up, long-sleeve shirt, with a maroon jacket with black accents, grey jeans, and dark grey boots.
- As he lives alone, Kai learned to cook for himself. One of his best dishes, which Miwa is impressed by, is beef stroganoff.
- Since he goes to Hitsue High School, it is most likely that he lives in Hitsue town.
- Kai's English voice actor also voices Blaster Blade in the V Series anime.