"Yasashii Suisei" (優しい彗星, lit. "Gentle Comet", English title: "Comet")^[1] is a song by Japanese duo Yoasobi from their second EP, The Book 2 (2021). It was released as a single on January 20, 2021, by Sony Music Entertainment Japan, and released as a double A-side CD single together with "Kaibutsu" on March 24. The song was featured as an ending theme song for the second season of the anime television series Beastars.

Following the release of "Kaibutsu" in early January 2021, Yoasobi announced the ending theme for the second season of the anime television series Beastars, titled "Yasashii Suisei". The song was based on the short story Shishiza Ryūseigun no Mama ni (獅子座流星群のままに, "A Leonid, Always"), written by Paru Itagaki, who also wrote and illustrated the manga.^[2]

"Yasashii Suisei" was released digitally on January 20, 2021, and released as a double A-side CD single, together with "Kaibutsu" on March 24. The single was released with two 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 videos from Beastars. The fan club limited edition also included the acoustic session of "Tabun" and "Ano Yume o Nazotte".^[3]

Later, "Yasashii Suisei" was included on their second extended play The Book 2, released on December 1.^[4] The English version of the song, titled "Comet" was included on the duo's first English-language EP E-Side, scheduled for release on November 12.^[5]

"Yasashii Suisei" is a ballad song with a straightforward message about two people from different backgrounds nurturing a beautiful friendship in a cruel world.^[6][7] The song is composed in the key of F major, 90 beats per minute with a running time of 3 minutes and 33 seconds.^[8]

"Yasashii Suisei" debuted at number 20 on the Billboard Japan Hot 100 of February 1, 2021^[9] and peaked at number 19 on the chart of March 31, 2021,^[10] and also peaked at number 97 on the Billboard Global Excl. US of February 6.^[11]

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,^[12] 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.^[13]

The music video "Yasashii Suisei" was premiered on March 25, 2021.^[14] It was directed and produced by Kōhei Kadowaki, who also produced the ending video for the anime Beastars.^[15] The music video focuses on the important characters of the anime, Louis and Ibuki, shows the ephemeral and gentle world view which flows between the two is delicate with over 2,500 illustrations drawn by director.^[16]

"Yasashii Suisei" was performed for the first time on the YouTube channel The First Take, which premiered on March 10, 2021.^[17] The duo gave a televised debut performance of the song at the 63rd Japan Record Awards on December 30, alongside "Kaibutsu", and "Moshi mo Inochi ga Egaketara".^[18]