St. Emilia Girls' Academy──. It is a consecrated world built on a small hill. It was known as a prestigious girls' school that incorporated moral education based on the spirit of Christianity. In a space far removed from the world, the girls grew up without knowing anything about impurity. But that was just a front face. Behind the scenes, it was running a large-scale 'mistress prostitution ring'. ＋＋＋＋＋＋＋＋＋＋＋ Tomoya is the only boy at St. Emilia Girls' Academy. He usually dresses up as a nun, but his job is not to serve God. A beautiful girl who is being sold will be trained to become a mistress that her owner prefers. Will he concentrate on his work and finally "ship" the girl? Or, as he gets to know her more and more, will his feelings shift...? It's your decision to make. And in the world full of lust, what truth will you find at the end of eros?