Cardfight!! Vanguard Gaiden: If

Kouji Ibuki is summoned to the Tatsunagi residence and abruptly thrown into an alternate world where history has been distorted and ordinary Cardfights no longer work. There he meets Emi Sendou, transformed into a magical girl, and Shuka, a mysterious card fairy. Together they form the Blaster Pair, summoning Vanguard units directly from cards to battle the servants of Jammer.

With Suiko Tatsunagi caught in the same disruption, the four travel through twisted versions of familiar events, repairing changes that have reshaped the lives of people they know. Yet the closer they move toward the source of the altered history, the more personal the cause of this strange world becomes.