Okuda Kosuke (Matsumoto Jun), a young man working for an advertising agency, followed his predecessor to visit clients. Unexpectedly, he met his first love girlfriend in his youth, Mao Watarai (Ueno Juri) at the other party's company. At that time, Kosuke (Kitamura Takumi) was studying in Enoshima, and a girl named Mao (Aoi Wakana) who looked cute but had poor brains and motor nerves suddenly transferred to the class. When Mao was bullied, Kosuke decisively helped her. After that, the two of them studied, chatted, and kissed together, and their immature love quietly bloomed in the sun until Kosuke suddenly moved away. Ten years did not separate Kosuke and Mao's thoughts, and their love was refilled with passion and warmth. The two fell in love and got married. When everything seemed to be heading towards the other side of happiness, Mao's body suddenly weakened rapidly. Kosuke didn't know yet that he would discover a sentimental secret that he couldn't let go of... This film is adapted from the original work of the same name by Koshigaya Osamu.