Amayakashi na Kanojo ~Boseiteki na Ayakashi Musume to Ama Ero Seikatsu Hajimemasu~

Our protagonist, Kuki Kizutaka, has had his body and spirit ruined by a black company. He visits a rural town to recuperate and, by a strange coincidence, he happens to meet some youkai girls and ends up living with them.

According to the girls, the protagonist's semen is precious and can increase youkai's magical power.

In exchange for pampering him, the girls ask for his semen...!

And so begins a naughty slow life with the youkai girls!!

Translated from the official website