Cardfight!! Vanguard Gaiden: If

Synopsis

After the Vanguard High School Koshien ends, Kouji Ibuki begins having vivid nightmares. Nome Tatsunagi sends Suiko to summon him to a mansion, where they learn he can perceive a Dark Tower called Sanctuary. This tower is distorting history across multiple timelines; the only solution is for Kouji to correct a future error he is fated to make. So Kouji and Suiko journey through the alternate world -if-, aided by Magical Girls Emi Sendou and Shuka, who summon Vanguard units to restore history. However, their efforts are hindered because fighting monsters via Cardfight proves mostly useless.