The former world was shattered by the war between humans and demon-kin. The only surviving royal of the defeated demons is the Demon Lord's daughter, Daqne, who returns to these former demon-controlled lands...

Masuda Keima, a lazy high-school boy who prefers to laze around and avoid working, gets summoned as a dungeon monster by a girl avatar named "Dungeon Core No. 695" who is the dungeon core of the mighty one-room...