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.

[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.

[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.

[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".