An unexpected death stripped Jongin's main source of happiness from him. Miyeon, his beloved girlfriend, a bright and loving girl, was killed in a car accident just nine days before their one-year anniversary. She left him a letter, expressing her happiness throughout the years that they knew each other. One year later, on the day of their anniversary, he received another mysterious letter from a person who claimed to be Miyeon. The mystery regarding her letter began to unfold as he tried to find the sender.

Three hundred fifty-six days, countless kisses, hundreds of hugs, and many arguments later...