There are a couple of main characters but they're just character archetypes. It's not important who exactly they are, but what they represent. The viewer sympathizes with them because they can easily insert him/herself into the roles. They're sort of abstract constructs designed to move the story forward and give the viewer an anchor to attach themselves to the narrative. The story itself follows the initial blossoming of the relationship between the main characters, then looks at its steady deterioration as time marches on. It's a powerful story because it's real and honest (maybe some artistic license in the first part). Apathy, indecision, and fear as well as time and physical distance all inexorably take their toll on the relations we've worked so hard to build over the years. To accept that is part of growing up; it's the only way people find closure. The ending (despite the jarring song, which I suppose has grown on me) is a wonderful montage that eloquently sums up a decade or so of those fleeting but permanent memories made between both characters. We should all be so lucky to have a music video commemorating those we've let slip away. C'est la vie.
A note on the visuals. Sometimes I just want to turn off the subs and watch this movie on mute because the visuals deserve to be appreciated sans distractions. The backgrounds Shinkai creates are the stuff of dreams. The narrative is interspersed with moments of sublime grace and elegance: a train runs over snowy tracks receding into the mists of memory; a lone crow soars through an impossibly gorgeous sky; Takaki gazes at a distant planetscape just beyond his grasp. Unforgettable. Sustenance for the soul. The first true work of art I've ever seen in this medium.
