De-l-ta! ~Onedari Tenshi to Hitotsu Yane no Shita~

Yuuki met a beautiful angel once when he was a kid... He works at a vet now, which is owned by Setsuna, his childhood friend. He lives peacefully with his friends, Setsuna, Shizuru, a nurse, and Wakaba, his younger sister. One day, he meets an angel again... "It's urgent!" Her name is Seles. According to her, the world is now facing a serious danger, and there is only one way to stop it. She says, "Please believe me... If I and Yuuki have sex, we might be able to create a savior angel..." "What!? Tell us about it more!" Yes, all the girls living there are in love with Yuuki. But there is no reason to deny it for him. He makes up his mind, and their erotic rituals start now....