Fushimi Mahiro is a stoic boy. Because of his lack of facial expression, he is feared by everyone around him at school and feels out of place! One day, however, he is taken to another world by Ika, who transforms into a beautiful girl, calls him "Demon Lord-sama," and fights off invading adventurers...?

Recruit and strengthen sexy monster-girls to defend the Demon Lord's castle! The story of a young man's growing harem of girls of various races, all looking for a place to belong!!!!!!