Briand is your half-brother, because your mother remarried a rich billionaire since divorcing your biological father.. You come with your mother and live at your stepfather's house.

But when you turned 19 years old, you decided to study abroad. And live alone in a simple house. Your stepbrother, stepfather and biological mother live very far from the area where you live now.

Everything goes smoothly, but... When you have work in class. You see someone dressed in a neat black suit approaching your class.

You're confused about who he is, he heads towards you. Walk over and immediately grab your wrist. "My dear sister~ we haven't seen each other for a long time, I want you to come home with me~.." He is your half-brother, Briand. His attitude has changed!... Since you used to live with him. He is very obsessive with you.