Jae-joong Kim, Do-hyeong Kim, Bumsu Lee, Soo Jung Yang
Ji Sub So, Ye Jin Son
"Mommy said she'd come back with the rainy season!"
"Wait for me. I'm on my way to be with you now."
Woo-jin lives alone with his young son, ji-ho, since his wife, Soo-a, passed away a year ago. Ji-ho believes his mother's promise of coming back when the rainy reason begins and waits. Then on a rainy, summer day, Soo-a appears miraculously before them just as ji-ho desperately wanted. Although Woo-jin is baffled, he tries to bring back Soo-a's memory of them, whom she does not recall at all, along with Ji-ho who is elated by his mother's return. While the three of them spend happy days talking about their memories together, Woo-jin worries about Soo-a vanishing once the rainy seaon ends.
When Soo-a accidentally finds out that she must leave when the rainy season is over in Woo-jin's diary, she also becomes sad and prepares to go. At last, the three of them confirm their love for each other and are forced to part again when the rainy season comes to an end. As Woo-jin lives on with Ji-ho without Soo-a, a letter she had written before she died arrives one day, and Woo-jin finds out about Soo-a's secret.