After being left by his best friends, Chanyeol decided to join a coastal clean-up. Expecting the usual garbage you'd see on the sea coast, he finds himself surprised when he spots a bottle containing various letters from the same person.

Soon enough, he finds himself immersed in the letters, and even finds two more bottles that contain the same thing. He realizes each bottle was written by a different person, and that one of the letters of the third bottle was dated only a few weeks back. He wishes to meet the author of the third bottle's letter, but he's met with another surprise instead.