Yoasobi (stylized in all caps) is a Japanese superduo formed in 2019 by Sony Music Entertainment Japan, composed of Vocaloid producer Ayase and singer-songwriter Ikura. Represented by the slogan "novel into music", the duo originally released songs based on selected short stories posted on Monogatary.com [ja], a social media website for creative writing operated by the label. Stories were later also sourced from various media like stories written by professional authors, books, letters, and plays, etc.
Rising to prominence during the COVID-19 pandemic in Japan, Yoasobi's debut single, "Yoru ni Kakeru", gave the duo the breakthrough by spending six non-consecutive weeks atop Billboard Japan Hot 100 and topping its 2020 year-end chart, as well as receiving the first ever diamond certification for streaming from the Recording Industry Association of Japan (RIAJ). It was followed by several successful singles, including Blue Period-inspired "Gunjō", and anime series themes: "Kaibutsu" for Beastars (2021), "Shukufuku" for Mobile Suit Gundam: The Witch from Mercury (2022), "Idol" for Oshi no Ko (2023), and "Yūsha" for Frieren (2023); "Idol" topped the Japan Hot 100 for 22 non-consecutive weeks—the longest-running number one in the chart history—and its 2023 year-end chart, and the Billboard Global Excl. US, the first Japanese act to do so.
Yoasobi released three Japanese-language EPs: The Book, The Book 2 (2021), and The Book 3 (2023), which all peaked at number two on the Oricon Albums Chart; and two English-language E-Side (2021) and E-Side 2 (2022). Beyond their discography, the duo collaborated with four Naoki Prize-winning novelists—Rio Shimamoto, Mizuki Tsujimura, Miyuki Miyabe, and Eto Mori—to publish short story collection Hajimete no in 2022, and performed songs based on each story. Yoasobi has earned several accolades, including five Japan Gold Disc Awards, three Space Shower Music Awards, four MTV Video Music Awards Japan, five CD Shop Awards, two Japan Record Awards, and a Noma Publishing Culture Award, among others.