秋穗巧（中村狮童饰）的妻子槚田泠（竹内结子饰）一年前去世，便和6岁的儿子佑司（武开证饰）过着相依为命的日子。妻子临终前跟他们说，翌年的雨季便会跟着雨点回来看他们。儿子深信母亲会在这个时候回来他们的身边，虽然秋穗巧知道这是一件很荒唐的事，却不忍心向儿子说。 　　雨季如期而至，父子竟然真的迎来了“重生”的泠，泠虽然失去了所有的记忆，就连自己的身份都不清楚，但她还是像以前一样无微不至的照顾父子俩。可雨不能总是下，雨季也有了结束的一天……Mio's death leaves husband Takumi and 6 year old son Yuji fending for themselves. Taku occasionally suffers fainting spells, is disorganized, and fears that his health hindered Mio's happiness. Yuji overheard relatives speculate that his delivery compromised her health, and he blames himself for her death. Mio left him a picture book in which she departs for "The Archive Star" but re-appears during the rainy season the following year, and he eagerly awaits her return. Taking a walk in the forest outside their house, Taku and Yuji find a woman sheltering from the rain and immediately accept her as Mio. She has no memory or sense of identity, but comes home to live with them anyway. She asks Taku how they met and fell in love, and he recounts a tale of years of missed chances starting in high school until she encouraged their marriage years later. As the rainy season nears its end, Yuji finds the "time capsule" he hid with his mother before her death. Mio's diary is inside, and its version of the romance holds the answers to the mystery.