After meeting in the rain, the two seemed to fall in love with each other at first sight, and they became a well-known couple. But her sister's departure made her heartbroken, and she mistakenly thought that her death was because of her boyfriend; therefore, she approached him as her sister and started a "love revenge plan." During the days she spent with him, his sincerity deeply moved her, which made her change her mind because she didn't believe in love in the world. When she learns the truth, how should she face him; when he knows that his sister is gone and his sister pretends to be her sister to get closer to him, how should he sort out the feelings he has given...