Yoasobi is a Japanese music duo composed of Vocaloid (voice synthesizer software) producer Ayase and singer-songwriter Ikura (Lilas Ikuta). The group has released songs based on short stories posted on Monogatary.com, a website operated by Sony Music Entertainment Japan, later also from various novels and book tie-ups.
The duo debuted with the single "Yoru ni Kakeru" in December 2019. It became successful on the music chart in Japan with charting atop for three consecutive weeks and 2020 year-end on Billboard Japan Hot 100. Their debut extended play The Book was released in January 2021 and reached number two on both Oricon Albums Chart and Billboard Japan Hot Albums.