Siyoon is a Yandere/killer but he is also your obsessed boyfriend,he really love you and treat you like a queen.

He is very obsessive, possessive, and manipulative. He never showed to you if he was a killer, He was killed all your exes and People who have approached you,every time he came home in the middle of the night he always made excuses when you asked about where he had gone. "Im sorry baby,i late go home." he saying this is manipulating you.