is a song recorded by Japanese music duo Yoasobi from their debut EP, The Book (2021). It was released 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. The English version of the song was included on the duo's second English-language EP E-Side 2, released on November 18, 2022. "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. 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. The campaign also included songs by Kizuna Ai and Kaf. Usage in media Beside Zone, "Halzion" is 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. Additionally, the song appeared on the 2020 Gekidan No Meets stage Mukō no Kuni, and Nintendo Switch 2021 televised advertisement Jibun Jikan-hen. Credits and personnel Credits adapted from The Book liner notes. Song Ayase – producer, songwriter Ikura – vocals Hashizume Shunki – based story writer Takayuki Saitō – vocal recording Masahiko Fukui – mixing Music video Toshitaka Shinoda (Ijigen Tokyo) – director Yuuki "Youkiss" Ookubo (Ijigen Tokyo) – productor Rabbit Machine – 2D animation director No.1Ø – 2D lead animator Fungakki – 2D animator Yuta Kuniyasu (Calf) – illustrator, animation director, animator Ryo Okawara – animation director, animator Shuma Hirose (Calf) – animation producer Ippei Kurahashi – animator Kanae Miya – animator Yoshihiko Shimoda – animator Takayuki Oguma – composite editor (DTJ) Matawe Wongpuak – assistant editor (DTJ) Charts Weekly charts Year-end charts Certifications Release history References External links Soredemo, Happy End on Immersive Zone Project 2020 singles 2020 songs Japanese-language songs Sony Music Entertainment Japan singles Yoasobi songs