Okite no Shima

The protagonist Asama Takamine is a special type of exorcist, who exorcises evil spirits by having sex with girls. He receives a job offer from a small island village.

There is a legend on the island that goes like this:
"When you become a woman, you must be with one who has power. Those who break this rule will be possessed by evil spirits."

On this island, girls must have their first sexual experience with the protagonist. It is believed that if you don't have an exorcist, you will be possessed. Asama visits the village for a ritual with the island's daughters. However, what he found was a girl in chains who had already been violated and was allegedly possessed...

[Translated from DLsite]