Following their intense battle in the national tournament, Team Q4 disbands, with everyone returning to their regular lives. While paying a visit to Card Capital, Aichi Sendou notices an unfamiliar customer in the shop. After teaching the secretive boy about Cardfight Vanguard, he realizes that his usual deck has become entirely different.

Although it contains a variety of units Aichi has never seen before, everyone insists that the cards are the same ones that he has always been using. Moreover, the strange boy disappears without a trace, leaving Aichi further puzzled. As Aichi gets accustomed to the new bizarre deck, he aims to unravel the mystery behind the incident and the peculiar boy.