NETORASE FANTASY ~Densetsu no Eiyuu wa Tsuma o Netoraretai~

After a fierce battle, Luke became a hero by defeating the root of the disaster. He and Mira, the princess he saved on his journey, become husband and wife.

However, Luke is worried that his peaceful life is not enough. He begins to wonder how he can satisfy his thirst. Then, a mysterious man appears to Luke.

The man leads him to a place where he learns about “Netorare culture” that is becoming popular among the common people. He is instantly drawn in.

Luke, who doesn't know that it is vulgar and the worst thing to do because he is a battle junkie, ends up degrading his wife.

[From official site]