Based on the erotic game by Lune.

Bad plan of the Principal of Women's School that made new policy and allowed a male student to attend and attend Ikenue Takumi Women's School. She plans to make Ikenue look strange and unnatural because she's just a male student herself. However, Ikenue wants to take revenge on them all after learning that the Headmaster has a magical item that is a Music Box with magical powers that can make people exposed to hypnosis.

(Source: Nekopoi and Has Been Translated and Edited)