Overview:

Late at night, at school is a game where you, the protagonist, will be served by three girls at a sex shop that is secretly open at night at school.
As a second-year student at Hoshiba Academy, you will have relationships with first-year student Yui Harukawa, third-year student Ayaka Himemiya, and modern literature teacher Nanami Tsukishiro at the sex shop, and gradually become closer to them.