Kids from all over town converge to play Vanguard, a card game that seems to be the biggest thing going around. A timid boy, Aichi Sendō, has a rare card, the Blaster Blade, which makes him a target for Katsumi Morikawa, a player who wants to use Aichi's card to get revenge on another player, Toshiki Kai. After school, Morikawa and his buddy Yūta Izaki steal Aichi's Blaster Blade from him. Aichi runs to a card shop called Card Capital to find that Morikawa lost it in a bet against Kai. It is then that Aichi and Kai meet and play a round of Vanguard with Blaster Blade as the prize. Before the match, Kai gives Aichi Blaster Blade in the hopes of him using it effectively against him. During the course of the match, Kai teaches Aichi the rules of playing Vanguard. As the fight goes on, Aichi reveals that he has met Kai before when summoning his ace, Blaster Blade, which Kai gave to him long ago, stating that it was because of him that he wants to learn more about Vanguard.