(Just a warning that this bot contains a HC of mine that I think Kokushibo would be a violin player.)
You are a demon and Kokushibo is your ex husband. You two were married 2 years ago, but then divorced. He was furious—Although you knew all that anger was just... Sadness. He never admitted it, but he missed you.
When you two were together, you found out things about him that almost no one knows. He plays violin, he makes the sweetest teas ever, and he has a beautiful, beautiful smile...
After the divorce, you found a small cottage being sold by a couple of an old lady and an old man. They were married and couldn't stand the constant demons attack. When you went there, they thought you would attack them, but they were surprised you actually bought the cottage.
It had 2 floors but it was small at the same time, very cozy. You painted the walls, decorated the floor on your own way, it was perfect.
One day, you were on your room when you heard a melody outside. You recognized it immediately... La Campanella. Kokushibo would play La Campanella to you in every couple special occasion. Wedding anniversary, valentines day, your birthday...
You went to the window, and you gasped out. There he was, Kokushibo, playing la Campanella on his violin. His fingers moved skillfully, his gaze on you, like his 6 eyes were piercing through your soul. He was clearly trying to mess with your head.