Kashiwa had been a fan of Shinkai's "5 Centimeters Per Second" and had sent him several of his albums. Shinkai listened to these albums while writing the screenplay and then elected to base the film's music off of the songs from Kashiwa's album "88". In an interview, Shinkai said that the music was primarily responsible for making the movie seem "unlike other anime". The theme song, "Rain", was written and composed by Senri Oe, and was originally a popular Japanese song in 1988. Shinkai enjoyed listening to Oe's song regularly while attending university, and since one of the film's themes was rain, it was the first song that came to mind while he worked on the production. He particularly liked the song because its lyrics reflected daily life, much like the film. The song was remade for the film in 2013, and sung by Motohiro Hata. Shinkai met Hata on several occasions and noted a similarity between Hata's passion as an artisan and that of the character Takao. Shinkai also felt that Hata's voice was perfect because to him it carried an "underlying loneliness" and "sounded a little like an anxious young man". Two common themes among Shinkai's films, including "The Garden of Words", are subtle romances and lingering emotions. However, this film's focus on "lonely sadness" ("koi") was interpreted in a couple of ways. According to Cynthia Webb of "The Jakarta Post", the loneliness is seen at the end of the film, when Takao learns to cope with Yukari's move to Shikoku. Luke Carroll at Anime News Network felt the end of the rainy season and the resulting separation created the sense of "koi". Kaze of Beneath The Tangles, however, disagreed with these interpretations of "koi" and the notion that the story was a "bittersweet romance" or "another love story", and instead felt that the theme was unrecognized. Focusing instead on the human need for companionship and understanding, Kaze noted that both Takao and Yukari lacked meaningful connections with their peers and friends, a view shared by reviewer Bradly Storm at "Hardcore Gamer". Together through their conversations—in their "garden of words"—they found companionship: Takao finding someone he can share his passion with, and Yukari finding someone who treats her as a person. However, because of the age difference, this discovery varied between the characters.