Mimibu's manga / #Human turned to demon(1)

10/10 Human summons demon and trades a wish for his life. His wish is too eat the demon. He does, but things also turn sexual in a twisted way. When demon takes his life, he decides to literally take his head and give him a new body and new life as a demon in the demon world. There's a lot to learn though. Twisted power Dynamics. J, the demon, gives instructions like riddles to solve. And out of unclear if the protagonist, Makoto, will have any friends. A potential friend is Fjord, who is the cute little demon who is J's reserved prostitute and who J instructed to take Makoto's virginity while J watched.