Kaibutsu
Background and release. On November 5, Yoasobi announced to writing and singing the opening theme song for the second season of the anime television series "Beastars", titled "Kaibutsu". The song was based on the novel , written by Paru Itagaki, who also wrote and illustrated the manga. "Kaibutsu" was released digitally on January 6, 2021, and released as a double A-side CD single, together with "Yasashii Suisei", titled on March 24. The single was released in 2 versions: limited edition (anime edition) and fan club limited edition for members of "Club Yoasobi", Yoasobi's official fan club website. Both  versions included the original songs, TV size version songs, and non-credit opening and ending video from "Beastars". The fan club limited edition also included the acoustic session of "Tabun" and "Ano Yume o Nazotte". Later, the song was included on their second EP "The Book 2", released on December 1. Yoasobi announced to release the English version of "Kaibutsu", titled "Monster" on July 30, alongside the accompanying music video, and aired the full song for the first time on their radio show "Yoasobi's All Night Nippon X" on July 27. It is the duo's third English song  after "Into the Night, and "RGB". Later, the song was included on the duo's first English-language EP "E-Side", release on November 12. Lyrics and composition. "Kaibutsu" is an upbeat fast-paced song with a catchy chorus, tells about a carnivore trying to coexist with herbivores in a cruel world. Although this idea is unrealistic, it still protects the herbivore. To adhere to its ideals, it decides to become strong and confront the whole world. The song composes in the key of A-sharp minor on verses and break, C-Sharp minor on the first chorus, C♯ major  on the bridge and in D minor in the final chorus, 170 beats per minute with a running time of 3 minutes and 26 seconds. Critical reception. American magazine "Time" ranked "Kaibutsu" number five on its list of the 10 Best Songs of 2021, becoming the only song from a Japanese act on the list, and being described as an "seamless" integration of "a giant pop hook with furious math rock riffs", "jazzy chromatic runs", and "a seismic EDM-esque drop". Additionally, critics said that the song gave "yearning", and "cinematic nature" and was "wholly unsurprised" to be served as  the theme song to the anime "Beastars". Commercial performance. "Kaibutsu" debuted at number 14 on the "Billboard Japan" Hot 100 of January 18, 2021 and peaked at number 2 on the chart of March 31, due to releasing the CD single. The song also peaked at number 87 on the "Billboard" Global 200 and number 39 on the "Billboard" Global Excl. US of January 30. The CD single "Kaibutsu / Yasashii Suisei" debuted and peaked at number 2 on the Oricon Singles Chart for the chart issue date of April 5, 2021, selling 23,761 copies, and also number 2 on the  Billboard Japan Top Single Sales chart, selling 27,275 copies for the chart issue date of March 31, 2021. Music video. The music video "Kaibutsu" was premiered on January 13, 2021, directed by Rina Mitsuzumi, with 2D animation by Kaori Onishi and motion graphics by Jun Matsuda and Cafuu. The music video depicts the conflict and determination of the main character, Legoshi, that wears a sense of speed and darkness. The music video surpassed 100 million views on June 22 and 200 million views on April 4, 2022. Live performance and cover. Yoasobi premiered the live performance "Kaibutsu" for the first  time in their first online concert—Keep Out Theater on February 14, 2021, where the song was the number fifth. The duo gave a television debut performance of the song at the 63rd Japan Record Awards on December 30, alongside "Yasashii Suisei", and "Moshi mo Inochi ga Egaketara". On February 4, 2021, A cover of "Kaibutsu" by Japanese singer Masayuki Suzuki was released as a promotional single from his 35th anniversary cover greatest hit album "Discover Japan DX", scheduled for release on February 23. Credits and personnel. Credits adapted from "The Book 2" liner notes and YouTube.