Aichi Send? is a timid third-year middle school student who has always lived his life looking backwards rather than forward. However, he has a card called "Blaster Blade" that was given to him when he was little, which is the sole thing that sustains him. Then Kai Toshiki, a cool-hearted high schooler, introduces Aichi to a card game called "Vanguard".
When participants battle they picture they are on a planet called "Klay", and since Vanguard features a never before seen game system it has become popular around the world. Aichi immediately likes Vanguard, so he begins to play it with his friends Misaki Togura and Kamui Katsuragi, and others like his new rival Kai (who is one of the best Vanguard players). Aichi plays every day and he strives with all his soul and heart to play better, so when he battles Kai, Kai will recognize Aichi's worth.