Isekai Seikatsu No SusumeIsekai Seikatsu no Susume; Devilish Darlings: Portal Fantasy; 異世界性活のススメ

Keitaro, who opened his front door one morning and suddenly transferred to a different world where demons and monsters infiltrated. Keitaro meets a young girl, Nia who is a semi-demon. Nia urges Keitaro to "make a child" with her. Apparently, a semi-demon woman can only have children with a human male ...