Muma no Machi Cornelica

Based on the erotic doujin game by Dieselmine (ディーゼルマイン). While working at a bar, the protagonist was asked to draw water. Upon picking up a mysterious stone he found there, he was whelmed by light. When he woke up, he finds himself in a country of succubi......! Various types of lewd demons draw near to him. He has to store a certain amount of magic energy in order to get back to his original world! What he will eventually face would be escape, or destiny to be a sperm slave forever... (Source: DLsite English)

Yuutousei Ayaka no Uraomote

An honor student, simple and pure who has no knowledge of adult things. One day a classmate asks her if she has a boyfriend, setting off a cascade of interest in sex and lust and debauchery.