Survive this unreasonable different world with 300 cards ─── !! After-school classroom where people are gone. As usual, Himuro was playing an online card game on his smartphone until the last minute of school. And … I found myself in a strange cave. There is a dungeon of the genie of another world. There, the helpless humans were nothing more than food for demons. A different world summoning battle fantasy that runs from the bottom to the strongest!