Uchi no Maou Kamimasen yo summary: In a world where people have supernatural creatures as pets, a certain family has a pet demon-lord Satan. The main carer of Satan is the son, Yuuhei. From initially coaxing the new Satan out of his pet-carrier, to walking him, playing with his ball, and keeping him from fighting with the neighbor's pet Hero, this is the comedic story of a boy and his Satan.