High school student Kinjirō Sakamachi starts his day with a painful awakening from his younger sister Kureha Sakamachi. Upon arrival at school, Subaru Konoe is seen as a student who works as a butler for Kanade Suzutsuki. Kinjirō has gynophobia, the abnormal fear of women, which is shown after a weird encounter with Nakuru Narumi. While cooling off in the restroom, he chances upon Subaru wearing girl's underwear, which results in Subaru chasing Kinjirō to the chemistry lab and attacking him for what he saw. When a jar containing a frog falls from the shelf, Kinjirō jumps in to save Subaru, but Kinjirō discovers that Subaru is a girl after landing on her chest. In response, Subaru throws a fire extinguisher at Kinjirō, which knocks him unconscious. He later wakes up in the infirmary chained to the bed with one hand free next to Kanade, who teases him a bit. She explains that the Konoe family has served the Suzutsuki family through lineage, in which Subaru, as the only child in her generation, must cross-dress as a boy to attend high school and continue serving as a butler. Kanade threatens Kinjirō with her sadistic behavior and forcibly forms a contract with him to keep Subaru's true gender a secret, as well as to find a way to cure his gynophobia.