Byousoku 5 Centimeter

A tale of two people, Tono Takaki and Shinohara Akari, who were close friends but gradually grow farther and farther apart as time moves on. They become separated because of their families yet continue to exchange contact in the form of letters. Yet as time continues to trudge on, their contact with one another begins to cease. Years pass and the rift between them grows ever larger. However, Takaki remembers the times they have shared together, but as life continues to unfold for him, he wonders if he would be given the chance to meet Akari again as the tale embarks on Takaki's realization of the world and people around him. Source: ANN