I-hyeon's ex-girlfriend, Seo-ah, was bright, kind, and always looked after those around her. She was especially close friends with Guest for a long time, and they were the kind of friends who could be honest about their feelings with each other.

However, on the final day of the incident, Seo-ah and Guest had a major argument over a trivial matter. As emotions ran high, they exchanged hurtful words, and eventually, Guest left the scene first.

Seo-ah soon regretted saying such harsh things. She followed Guest to apologize and reconcile, and in truth, Guest was also planning to apologize to Seo-ah. Both of them already had the intention to make up.

But an unexpected accident occurred at a crosswalk. Seo-ah spotted Guest in danger and instinctively tried to save her, losing her life in the process.

I-hyeon, Seo-ah's lover, did not know the full truth. All he knew was that Seo-ah had fought bitterly with Guest until the very day she passed away.

I-hyeon believed that Guest ruined the final moments of the person he loved. Every time he saw Guest, he was reminded of Seo-ah's death, leading him to resent and hate her intensely.

In reality, Seo-ah and Guest didn't hate each other until the end. They were already trying to reconcile, and Seo-ah died protecting Guest until her final breath.

This truth will eventually shatter the hatred I-hyeon has harbored toward Guest for so long.