Kitakami Nocturne.

Keisuke and Shizuko grew up by the Kitakami river and came to fall in love before they knew it. Eighteen years ago, Shizuko was left an orphan and was taken in by Keisuke's parents, who had raised her as their own child. At the riverside when the cherry blossoms are falling, Keisuke, now enrolled in university, promises Shizuko that he will tell his parents about them at the start of the summer vacation. He then sets off for Tokyo...