Love Letter

is a song by Japanese duo Yoasobi from their second extended play, The Book 2 (2021). It was released on August 9, 2021, through Sony Music Entertainment Japan. The song was written by Ayase and based on Hatsune's letter Ongaku-san e, which won the Letter Song Project, a collaboration with radio show Sunday's Post. "Loveletter" peaked at number three on the Oricon Combined Singles Chart, and number four on the Billboard Japan Hot 100. Background and release On August 30, 2020, Sunday's Post, Tokyo FM's radio show owned by Japan Post Service, announced a collaborative contest with Yoasobi called Letter Song Project to perform a song based on a letter written by listener about thoughts or expectations under the theme "thank you". The winner was announced on July 25, 2021, as sixth-grade student Hatsune's letter, titled , which spells out gratitude for music. The song, titled "Loveletter", was aired for the first time on the radio show on August 1, and released on August 9 to digital music and streaming platforms. Later, the song appeared on Yoasobi's second extended play The Book 2, released on December 1. The English version was included on the duo's second English-language EP E-Side 2, released on November 18, 2022. Composition and lyrics