In 1999, Eun-joo moves out of her house "Il Mare", leaving behind a Christmas card for the house's eventual new owner, asking him/her to please forward any mail of hers to her new address in the city. It is 1997 and Sung-hyun, the first owner of "Il Mare" is moving in and finds in his mailbox the Christmas card from Eun-joo. Thinking it is a joke, Sung-hyun leaves her a letter telling her so and reminding her that it's 1997, not 1999. Eventually the two realize that they are separated by two years of time but can somehow communicate through the mailbox and form a friendship through their letters.