On Christmas Eve, Hiro Hirono meets a girl named Miyako Miyamura as she chases a purse snatcher. Hiro later finds out that Miyako also goes to the same school as he does and they start hanging out together. This makes Hiro's childhood friend, Kei Shindō, feel left out, so she tries to compete with Miyako for Hiro's affection, creating a love triangle. Meanwhile, Renji Asō meets a girl named Chihiro Shindō at an abandoned train station. He soon learns that Chihiro suffers from a type of amnesia where her memory lasts for only 13 hours. He also discovers Chihiro's dream of writing a novel, but she has never been able to fulfill that dream due to her condition. Renji then decides to help her fulfill that dream.
Episode 1
Kyosuke Tsutsumi spots a beautiful girl and tries to photograph her. Hiro Hirono meets the beautiful Miyako Miyamura when she steals his bike in pursuit of a purse thief. Renji Aso encounters the mysterious Chihiro Shindo at an abandoned train station.
Episode 2
Kyosuke questions his ability as a photographer. Hirono spends the day with Miyako. Chihiro reveals to Renji that she has a memory defect that only allows her to remember the last thirteen hours.
Episode 3
Renji rethinks his arrangement with Chihiro. Miyako walks out on Hiro. Kyosuke makes some major changes.
Episode 4
Renji sees Chihiro for the first time after she gets over her cold and apologizes for not coming last time. Renji asks her if she would like to write a novel with him, as she had said earlier that it was her dream to write one, but Chihiro gets very defensive and angry at his request. After talking with her more on the issue, Chihiro finally gives in to his persistence. Kyosuke sees Kei again in town and finally realizes she was the one he filmed on Christmas. Hiro meets with Miyako in town and she goes back to his place while he works on his manga. Miyako reads some of Hiro's manga, and as an act to show her gratitude, she cooks food for him. Kei walks in on them together, and runs off.
Episode 5
Renji is concerned with Chihiro's manuscript, Miyako refuses to leave Hiro alone, and Kyosuke gets Kei's attention.
Episode 6
Kyosuke's interest in Kei wasn't straightforward, Kei ruins Mikyako and Hirono's date, Renji and Chihiro sneak into the library.
Episode 7
After getting a significant amount of work done on the novel, Renji and Chihiro go for a walk on the beach where a misunderstanding causes Chihiro to run away in tears. Kei further sabotages Miyako's relationship with Hiro.
Episode 8
Hiro reaches out to Miyako, while the frantic pace Chihiro has been working causes her to collapse.
Episode 9
Hiro and Miyako take their relationship to the next level, causing Kei to melt down emotionally. Renji pushes on with the work, despite Chihiro's change in personality and the pain it causes him.
Episode 10
Hiro and Kei come to an understanding, but Miyako is pulling away from him.
Episode 11
Chihiro finishes her novel and agrees to go out on a date with Renji.
Episode 12
A depressed Renji reflects on his memories with Chihiro and begins to collect her missing diary pages. They meet again at the train station. Yuko and Yu reunite at the old church, and all is well for the other couples.
