Ami, a backpacker from Japan who is four years older than high school student Jimmy, shows up at his part-time job. The two end up spending the summer working at the same store, but Jimmy gradually develops a faint crush on Ami. The two of them grew closer as they rode motorcycles together at night and went to the movies, but suddenly, Ami decided to return to Japan. Ami proposes her "one promise" to Jimmy, who can't sort out his feelings. As time passes, Jimmy visits his parents' house for the first time in a while and finds a postcard that Ami sent him 18 years ago when she returned to Japan. Jimmy's memories of his first love come back to him, and he takes his first solo trip to Japan to confront his past and examine his present. Jimmy rides the train while listening to songs that remind him of his memories with Ami, and he heads to her hometown. Will Jimmy be able to reunite with Ami?
Hitomi, a Japanese resident, comes to Hong Kong after the death of her fiancé Tatsuya in a fatal accident to settle several important matters surrounding his demise. Although the incident was years ago, it has apparently left an indelible mark in her life as she could not forget him. Kar Bo, an undercover cop, was involved in a drug bust-up which would later incriminate him. Hitomi stumbles into him and was amazed that he looked remarkably similar to her dead lover. Although Hitomi was conscious that Kar Bo can never be the real Tatsuya, she endures his hardships with him unfailingly which results to having strong feelings for each other.
Mika goes all the way to Seoul to see her sweetheart Hyeong Jun who's been waiting for her. She suffers faints at the airport and she mistakes Kim Gyeon as Hyeong Jun due to trauma. Kim Gyeon also ends up falling in love with her, thus disrupting the balance between the three. Their memories start intertwining, but, before long, a tragedy occurs
Emilia, a Filipino who arrived in Japan with aspirations of becoming a model, coincidentally encounters Matsuyama Mirai, an aspiring photographer. Their connection deepens as they find themselves drawn to each other. Mirai, intent on immortalising their moments together, diligently captures their essence through the lens of his camera. However, an unexpected parting disrupts the flow of their narrative. Subsequently, the saga of these two individuals unfolds beyond the shores of Japan, traversing the vast sea to the Philippines, where their story takes on new dimensions.
L, an angel who’s endlessly fascinated with the human world, gets into trouble when she unthinkingly saves the life of Han Shi Yeong, a man who was meant to die. To make up for her mistake she must guard him on Earth for one hundred days and keep him safe from Hwan, a death god who is required to collect his soul. Both supernatural beings must contend with the knowledge that whichever one of them fails by the end of the hundred days will be erased from existence, and the longer they stay on Earth the further their powers fade and the more human they become.
Singer Hyeon Seok develops problems with his hearing (Menieres syndrome) and has to stop his recordings. He notices a picture of Hokkaido in a magazine and decides to travel there. He eventually arrives in a a small village in Hokkaido for rest. While there, he reminisces about the old days. The owner of the inn offers him a Japanese meal. There he meets a bright cheerful girl named Megumi.
