is a song by Japanese duo Yoasobi from their debut EP, The Book (2021). It was released as a single on December 18, 2020, through Sony Music Entertainment Japan. The song was based on short story, Tsuki à Âji ( "Moon Prince"), written by screenwriter Osamu Suzuki. The music video premiered alongside the single release. The English version of the song was included on the duo's second English-language EP E-Side 2, released on November 18, 2022.
"Haruka" was described as a song about encounter and farewell, drawn from the perspective of "something" that has watched over the growth of a girl more than anyone else. It is composed in the key of C⯠major at 100 beats per minute with a running time of 4 minutes and 4 seconds.