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!