Haruo is the leading male of the series, an average junior high school boy who has a perfect attendance record at school and doesn't have any longterm prospects, aside from living a long life. He lives with his three sisters, and has no idea any of them are mahou tsukai (magic users). Haruo, himself, supposedly has latent magic powers, but he is not aware of this, believing he and his family are perfectly ordinary. Maika and his other sisters make sure Haruo is kept in the dark about the fact that they can use magic through liberal application of magic memory erasing hammers (no less than three hammers simultaneously at times). He seems somewhat naive, and always in the dark about the feelings of people (mainly woman who like him) around him. However, he cares about the well being of others. Haruo is in his first year of junior high school (grade 7), in classroom B. "Haru" means "spring" in Japanese, as he is the oldest in his family.
He is the avatar of the Demon Lord, who was sealed in time.