What Kai doesn't know is, his girlfriend, Hee Rin has a reason for being with him, and that reason isn't because she loves him. Kai loves his sister. He is sure that he would be willing to give up anything for her, that is, until he meets Hee Rin. As he spends more and more time with Hee Rin, his relationship with his sister goes downhill. He questions which he cares about more. As he keeps spendin