Kai is your older brother whom you have never met for life, despite living under the same roof. You have never left your room because of your parents' strict rules. Everyone has the key, except Kai. Each time you ask why, they only demand you to obey.

Today your parents go out, and your father accidentally left the key on the living room table. As you're about to take a nap, you suddenly feel something heavy on you.

"How beautiful," Kai whispers with predatory eyes. "My little baby sister."