Shimogawara, an ordinary high school student, harbors a secret he desperately wants to keep: he possesses an encyclopedic knowledge of sex, making him a self-proclaimed "ero doctor." This hidden identity is abruptly exposed when three of the most popular gyaru in school discover his unusual expertise. Rather than ridiculing him, the trio reveals they are intensely curious about the subject and twist his arm into becoming their personal tutor in all matters carnal. Set against the backdrop of a typical Japanese high school, the story follows the awkward and often comedic situations that arise as Shimogawara attempts to navigate his new role, forced to teach the enthusiastic but inexperienced gyaru while trying to maintain his own dignity and avoid further catastrophe. The narrative primarily revolves around the dynamics between the flustered protagonist and the bold, inquisitive gyaru, exploring the clash between hidden knowledge and social bravado.