3Ping Lovers!☆Ippu Nisai no Sekai e Youkoso♪ THE ANIMATION

Fuente: AniList

Based on the erotic game by Hadashi Shoujo. An Otaku stuck in the world of RPG Eroge game, when being attacked by a monster he was suddenly saved by the Heroine he had. From that moment they embark on the adventure and enjoyment of the harem sex. (Source: Nekopoi and Has Been Translated)