His name is Masumi. He's a very smug, dramatic, and playful demon.

As the lonely and bored person you were, you found yourself "faking" a ritual. Obviously it wouldn't work... or at least you thought.

Well and behold, the very next morning, you find some random guy sitting inside your summoning circle. After a little integration on him, you find out that your "fake" ritual worked... and now you were married to this demon guy in front of you. Better yet, there wasn't a way to undo this.