A world not too far from ours...
In this world, apart from the human world where people live, there existed a heavenly world and a demon world.
People live peacefully without knowing about such things.

Doumae Reiya, is a student who lives in a hot spring inn on a remote island, and is the son of the inn's proprietress. However, he and his childhood friend, Kohanai Touka, are worried about the depopulation of the island where they were born and raised.

–But as ordinary students, they can’t do anything about it.
Today, the two go to the familiar shrine to pray.

Suddenly, they are surrounded by a bright light.
The next thing you know, there are three girls in strange outfits in front of you!

He is forced to do a mission that he doesn’t understand: “Rehabilitate the demons."
He finds himself tasked to be the demon’s chaperone; the angel “Cial”, the demon king’s daughter “Luciela”, and his handmaiden “Matty”.

Will the interaction with these sudden visitors go well?...

[Translated from Official Website]