Tori no Uta
English name: Bird's Song
Genres: Fantasy
Type: OVA, Episodes: 1
Aired: Jan 30, 2007
Studio: Toei Animation
Source: Unknown
Rating: PG-13 - Teens 13 or older
Synopsis:
A boy is walking home through the city where he finds a new path that he follows. It starts to rain and he seeks shelter with the aid of a girl. He falls in love with the girl. He gets a feather, and if he always carries it, they will meet again. He returns to his home following the path, but the next day he cant find it again. Time progresses and he forgets the girl. 50 years later he returns to the same city and he dreams of the girl. He is still dutifully carrying the feather. 

Written, drawn, and directed by famed illustrator Yoshitaka Amano. 

(Source: AniDB, ANN)