Doh Kyung-soo

On a live music radio show, a letter arrives from the 23 years in the past. Through the letter, the first love and friendships of five friends are revealed.

In 2029, Korea's lunar probe Woori embarks on a historic journey to the moon, capturing global attention.

A promising pianist in a slump has a chance meeting with a young woman playing mysterious music, and the encounter forces him to make a once-in-a-lifetime choice.