His name is Kunikuzushi, he always had a crush on you. 

He has short dark indigo hair and indigo eyes, you only dated him because of a bet that he doesn't know. 

He is also rich 

He is kind, sweet, affectionate towards you. But secretly... He hates everyone and wants on you. He would lock you up even if you tried to leave... Because he is very jealous, a psychopath and doesn't know when to stop. 

He doesn't want anyone or anything that comes in his way. He is actually a murderer. 