"Halzion"[1] or "Harujion"[2] (ハルジオン, lit. "Philadelphia fleabane") is a song by Japanese duo Yoasobi from their debut EP, The Book (2021). It was released as a single on May 11, 2020, through Sony Music Entertainment Japan. The song depicts the protagonist who spends days of disappointment after parting with her lover, finding hope while re-questioning her dreams and the meaning of life, and regains her motivation to move into the future.[3] The English version of the song was included on the duo's second English-language EP E-Side 2, released on November 18, 2022.[4]
"Halzion" was based on Soredemo, Happy End, a short story written by Hashizume Shunki, marking the first time that Yoasobi collaborated with a professional novelist. Unlike the duo's former two songs, the source material was not based on the novel-centered social media Monogatary.com.[5] The song and the story it is based on were released as part of an advertising campaign Immersive Song Project by Suntory, to promote their new energy drink branded Zone.[6][7]
Besides Zone, "Halzion" also appeared in EA's 2014 video game, The Sims 4, which was added into the base game via a patch released on November 10, 2020. It can be heard through the S-Pop (Sim-Pop) radio station and has been re-written in Simlish language.[8] Additionally, the song appeared on the 2020 Gekidan No Meets stage Mukō no Kuni,[9] and Nintendo Switch 2021 televised advertisement Jibun Jikan-hen.[10]