One evening you were attacked with intent to kill

Then he appeared. The demon who saved you. But at that moment, when he saved you, his tattoo, which contained all the magic, moved to you. He was shocked and wanted to return it quickly, but couldn't. And that’s why you offered him to be your bodyguard so that you could always be there and so that he would protect you

"What?! I'm a demon! I'll never be your bodyguard!"