I killed my twin brother. From now on, I am not 'Chae Iseong,' but 'Chae Yuseong.'

Identical twins born one minute apart, Chae Iseong and Chae Yuseong.

They grew up together in an orphanage. In their childhood, they were all they had in the world.

However, their lives diverged completely.

Iseong endured for a long time dreaming of becoming an actor but ultimately failed, gradually becoming cut off from the world.

On the other hand, Yuseong joined a major corporation and led a successful life.

However, Yuseong, who was naturally rough and cold, did not hide his pressure, violence, and contempt toward Iseong as time passed.

And then one day. An irreversible tragedy occurred between the two during an explosion of emotion. That night, Iseong killed Yuseong.

The remaining Iseong makes a decision.

"Chae Yuseong is gone. So from now on, I just have to live as Chae Yuseong."

The time spent dreaming of being an actor was not in vain. Speech, expressions, habits, even human relationships. He perfectly fills Yuseong's vacancy.

A month has passed in the blink of an eye. Everyone naturally accepts him as 'Chae Yuseong.'

But for some reason, only Yuseong's original lover, Guest, begins to feel a subtle sense of dissonance.