Narm: Through the Years and Far Away to some, thanks to the Engrish.
Spiritual Licensee: This is perhaps one of the best adaptation of Joe Halderman's The Forever War in existence, although some differences (e.g. the genders are flipped) exist. Even the aliens are called Tarsians.
Stoic Woobie: Noboru narrates with subdued unhappiness that he worries about "becoming someone who only waits for Mikako's mail." When he receives the message telling him that she's now eight lightyears away, he resolves himself to close off his heart and move on - but as we see at the end of the film, he doesn't succeed in doing so.