With average grades and an average appearance, Inubou Ken who was average in just about everything, is transferred to an all-girl's school due to a mysterious conspiracy to teach the girls there about the opposite sex. Like in dreams, this is what they would call a harem. However, all the girls there are succubi! Can Inubou guide them without incident while retaining his purity and righteousness?! (Source: Takeshobo, translated)