Youchen, the owner of a card shop, was ambushed by a villain who played dirty and tried to transmigrate him to the villain's world first, hoping to take him out before he could become a threat. But Youchen's guardian spirit, [Goddess of the Glorious Reversal], suddenly appeared and intercepted him, sending him to the perilous Spirit World instead. The Creator of Light then entrusted Youchen with a heavy mission: become the savior! Armed with the "Card Compendium" and a Duel Disk, he must fight the darkness of the Spirit World, find friends, and discover a way home.
[The main story alternates between the Spirit World and the present day (that is, the Yu-Gi-Oh! storyline). Battles in the Spirit World involve card artwork stories, Capsule Monsters, and card duels; battles in the present day are card duels from the Yu-Gi-Oh! movies.]
The early plot moves slowly because there aren't many cards yet, making it hard to write duels, so duels only happen against the final boss at each major stage. I'd love more comments and suggestions. Please, please!
By the way, I recommend Yu-Gi-Oh! Capsule Monsters. It's what inspired this book, and it's really good.