(A note before reading: this book is purely the product of the author's wild imagination run amok. Please don't expect anything from the prose, thank you.)
This is a story about one card, or many cards, and a world.
Transforming into spirits from Yu-Gi-Oh! cards and causing trouble in all kinds of worlds: doesn't that sound incredibly exciting?!
In this book, you might see Kamen Rider Saber, Mathmech Sigma, and the Sacred Beasts; the Fate world, Fallen Angel Lucifer, and D/D/D monsters; Ultraman, Dracotail, and Kaiju Neos coming together; Super Sentai teaming up with Super Quant; and card spirits taking on other forms and causing trouble in all sorts of animated universes.
In short, this is a completely unrestrained work of wild imagination, where the author writes whatever comes to mind and never gets writer's block. Look forward to it.
(Current world: Mathmech and Saber)