The "heart-warming comedy" anime centers on Chimimo, who is a messenger of hell and a shape-shifting evil demon. Chimimo is one of 12 evil demons whose mission is to turn the human world into hell. The 12 demons along with "Hell-san" go to the human world, but Hell-san and Chimimo become freeloaders to a family of three sisters named Mutsumi, Hazuki, and Mei.