Secret Rites with the Holy Maidens Vol. 1

A sexy isekai story about giving holy maidens a bit of sexual education.

After spending the night playing the latest 18+ game, Itsuki Kusaka finds himself waking up in an entirely different world! Despite the fact he has no desire to be a hero, his attitude changes when a giant, naked goddess tells him the details of his mission. All Itsuki has to do is teach her disciples a thing or two about sex. With hands-on learning, of course. 

Is this a dream come true for this adult gaming fan or will Itsuki find his mission to be more challenging than he expected?