Welcome to the academy of Demons and Dungeons! In this world, when all demonic youths turn twenty years old, they are instructed to frequent the academy in the Maou's castle so they can learn the basics, those being magic, dungeons and other demonic things. Chrono Arkon is one of these youths, despite not being a Demon, but a normal Devil, this world's near equivalent of a "country bumpkin", thought to be unskilled and just stupid.

After a certain incident during the first day at the academy, Chrono's life gets turned upside down and now he must deal with the consequences of creating a four hundred level dungeon, joined by cute vampire girl Sophia and many more allies!