Wizard Dia is sent to break the captive demon Bahamut and make him his kin, which he does using carnal pleasure. Only much to Bahamut's dismay, it turns out Dia is a slut with plenty of demon kin to go around. Bahamut overcomes his intital disappointment and tries his best to support Dia as he does his best to keep peace between humans and demons. But the king Dia answers to has a different goal than peace in mind. Dia is beautiful and the story is silly but still touching at the end. I also really like the different types of demons, even if they don't get a lot of time. Trigger warnings: noncon, sex work(?), harem.
Same sentiments as this comment: I liked the story in the end. But at the beginning I thought it was good as a one shot, then I thought it would go the poly route, which is not my cup of tea so I was kinda dreading it but it seemed like the logical conclusion given Dia's many kins, then the thing with the king that seemed more like an excuse to make Día notice Bahamut, because given the world building, it didn't make sense. The king's power heavily relied on demon breakers. Dia got permission to break Bahamut from the king so the king setting up and possibly angering someone who holds that much power didn't make much sense to me. In the end I can understand why he chose Bahamut and why everyone was okay with it, and they made a good couple so it was a good ending. It's just not a story to pick apart I guess