Hell is ruled by three Demon Kings: Death Mask, Giant Lock, and Dark Night. Using their authority to live as they please, they command the sinful dimension's denizens to do their bidding and make sure to punish any humans who enter their territory.

This all changes, however, when their minions find a human child during one of their daily investigations. Death Mask finds himself unable to order an execution, gradually falling prey to the three-year-old's innocence. Naming him Maris, the Kings take on the role of the child's guardians, and the daily antics of demons raising a human begin!

[Written by MAL Rewrite]