Takaki Toono and Akari Shinohara's love runs deep, but it seems as though fate has different plans in mind for them. Despite having been close friends since childhood, circumstances beyond their control have caused them to be separated. As time passes and the distance between them grows, their memories of each other never fade as they promise to keep in touch. Byousoku 5 Centimeter delves into the hardships and struggles that come with having a long-distance relationship, where Takaki and Akari are unable to move on from the past and create new memories. Consequently, they find themselves living aimless lives, which not only inflict pain upon themselves but the people around them.