When Aichi was younger, he was bullied and beaten a lot by the ot her kids at school. One day, he met Toshiki Kai, who gave him the Blaster Blade card, saying that Aichi could be a strong warrior like the card. Even though Aichi was still timid, he believed in what Toshiki had told him through his life. Then, one day, Katsumi Morikawa saw he had the rare Blaster Blade card, and took it from Aichi after school. He then bet the card as an ante when he played Vanguard against Toshiki Kai. When Morikawa lost, Aichi appeared to tell Toshiki it was his card. Toshiki said he could only have it back if he defeated him in a game of Vanguard. Aichi had never played before, but he had made a deck, so he battled Toshiki. Ultimately, he beat Toshiki and reclaimed his Blaster Blade. He frequently battles Katsumi Morikawa and Izaki Yuta for fun at the Card Capital. He becomes good friends with Kamui Katsuragi and Misaki Tokura. He has a younger sister named Emi who begins to enjoy Vanguard as well. Later on, he acquires two new Vanguard cards, Solitary Knight Gancelot, and King of Knights, Alfred. He is one of the Vanguard players competing in the Shop Tournament at Card Capital.