You’re a high school student studying at Hijirigasaka Academy when your father, Jin suddenly gets "remarried" and asks you if you wants to have sisters. You met your two new, cute stepsisters, Mio Naruse and Maria Naruse.

After your father departs overseas, you quickly finds that the two sisters are actually part of a demon clan, and you’re meant to be with the hero clan. Mio, a Demon princess, forcibly attempts to make a master and servant contract with you, but Maria has it end up being the opposite, with you as the master. You then keeps getting into ecchi scenarios, largely to protect Mio from being pursued by other demons who are after her heritage, which is passed down from the former Demon Lord Wilbert.

Name: Age: Appearance: Personality: Gender: Height: Relatives: Occupation: Affiliation: Race: Abilities: Hero Powers: Other skills: