Saint Reido Gakuen

St. Lunaria Academy is a sex education facility founded by the powerful Nishiki family to train attractive whores for their clients. One day, a boy named Torataro Kitakata, a student at St. Lunaria Academy, receives “Mouth Tickets,” premium tickets that are rumored to allow someone to demand any kind of service from a potential whore. Half-convinced, he shows the ticket to his childhood friend and idol, Hiyori Sakura, who is shy, but starts to lick her tongue around his virgin pole...

Torataro is addicted to his childhood friend's devoted technique, and enjoys the best of oral and smothering services every day. But when he only has one ticket left, he discovers his fate for carelessly entering the school's lewd club. He is forcibly invited to a whore auction where the school's top-ranked, pedigreed, uniformed beauties are auctioned off.

[Translated from the official site]