Goon appears as a witness at the ethics committee hearing. Goon and Shin receive a photo of Shin's stalker and learn that the stalker is Sae Yan's biological father.

Ju-yeon faces a life-threatening crisis after confronting Sae-yan's biological father.

Teo succeeds in the 109 mouse reset experiment and becomes the leader of the research center. In order to find Sae-yan's biological father, Kun and Sae-yan look for old newspapers.

Lee Shin's attempted murder is revealed on the internet. Kun gets the black box video that recorded the incident and learns the truth.

Joo-yeon and Shin save Kun who fell into the water. Joo-yeon finds Kun's diary. Shin secretly burns Kun's emotional diary.

Joo-yeon and Kun stay at Kun's grandmother's house. Kun manages to stop Sae-yan's mother, who comes to take Sae-yan away.

The national tennis athlete training day has begun. Sae-yan, who is being chased by his family's men, runs away with Kun, Shin, and Joo-yeon.

Shin and Joo-yeon almost get caught by Kun. Si-on runs away from the filming location. Kun loses to Chairman Hong in the fight for investment.

Sae-yan who becomes a translator for foreign coaches. Lee Shin finds out that Joo-yeon is not Lee Kun's first love. They work together to lie to Kun.

Sae-yan returns to Korea to find someone. However, Shin has a fight with Sae-yan and returns to Seoul alone. Joo-yeon and Kun pick up Sae-yan.

Lee Kun rejects Joo-yeon who wants to work as a team doctor at his agency. Joo-yeon offers Kun a deal.

Joo-yeon is also present when Kun meets with investors. Joo-yeon also finds out about the relationship between Dr. Teo and Dr. Yeo.

In order to get a contract with Si-on, Kun picks up a tennis racket again. Joo-yeon sneaks into Kun's house to look for her swapped documents.

Joo-yeon confronts Kun. Lee Shin keeps Kun's accident a secret. He is attracted to Joo-yeon after the consultation. Sae-yan appears.

Kun successfully erases his bad memories through surgery and lives a new life. He immediately meets Joo-yeon, whom he thought was his first love. Joo-yeon hides the side effects of the surgery.

For fifteen years, Lee Kun lived as his younger brother's shadow. Then, he met Joo-yeon, a psychiatrist who changed his life.