Aizaki Koi is the granddaughter of the head of the board of directors in Tenjou Gakuen, an elitist boys school. One day when she was walking home from school, two strange men in black beckoned to her, telling her there is something her grandfather wishes to speak to her about.
At first, she was skeptical about the purposes of these men, however, when the voice of her crush and cousin Hayami Naohito calls out to her, she losts her skepticism and blindly follows them to the car. When she realizes they have taken her to her grandfather's school, she knows something is wrong.
But it is too late, for her grandfather has already dealt his damage. He has taken her out of her old school and enrolled her into his boys school to prove to the board of directors that changing the boys school to a co-ed system is good for the school's development.
Koi is obviously opposed to the idea and her grandfather's way of doing things, but the violent outbursts from the board of directors inflames her and before she knew it, she has decided to join her grandfather on his little crusade.
Being an only girl in a boys school gives Koi and the players plenty of opportunities to (re)experience teenage romance. But aside from romance, can the strong willed Koi change the board of directors' minds about the school system?
