Yoasobi is a Japanese musical duo formed in 2019. It consists of songwriter and producer Ayase and vocalist Ikura. Represented by the slogan "novel into music", the duo's narrative-driven songs are originally based on selected fictional stories posted on the website Monogatary.com. Later, sources also come from various media, such as fiction written by professional authors, books, letters, messages, plays, and social media posts. Known for its fast pace and complex structure, their music has been characterized as a blend of J-pop and Vocaloid music.
Rising to prominence during 2020 in Japan, Yoasobi's debut single, "Yoru ni Kakeru", topped the Billboard Japan Hot 100 for six non-consecutive weeks and its 2020 year-end chart, the first ever non-CD single to do so, as well as receiving the first ever diamond and double diamond certifications for streaming figures from the Recording Industry Association of Japan (RIAJ). Three other songs were also certified diamond: Blue Period-inspired "Gunjō" and anime series openers "Kaibutsu" from Beastars and "Idol" from Oshi no Ko. The latter set the record for the longest-running number one on the Japan Hot 100 history with 22 non-consecutive weeks, the first Japanese act to top the Billboard Global Excl. US, and was one of the best-selling songs worldwide in 2023. Several publications dubbed the duo a representative of J-pop of the 2020s and the Reiwa era.
Yoasobi's first four EPs—The Book, The Book 2 (2021), The Book 3 (2023), and The Book For, (2026)—explore the "reading CD" theme and peaked in the top ten on the Oricon Albums Chart. The duo entered the English-language market by translating their songs into English and releasing the E-Side EP series. Furthermore, the duo also collaborated with four Naoki Prize winners in the short story collection Hajimete no and performed songs based on each story. Yoasobi has received many accolades, including CD Shop Awards, Japan Gold Disc Awards, Japan Record Awards, MTV Video Music Awards Japan, Music Awards Japan, and Space Shower Music Awards.
Name
The duo's name, Yoasobi, originates from the Japanese word , literally meaning "nightlife". Ayase, who came up with the name, explained that it expresses his wish for him and Ikura to take on various playful challenges, comparing their individual careers to daytime and Yoasobi's to nighttime. The duo represents themselves by the slogan . When the song is not based on a fictional story, the duo will credit separately, as Ayase and Lilas Ikuta. The official fanclub is Yoa's (pronounced yours), which officially changed from in October 2025.
History 2019–2021: Formation, "Yoru ni Kakeru", and The Book
Both members of Yoasobi had active music careers before the formation. Ayase was active as a vocalist for the rock band Davinci from 2012 to 2018; the band disbanded in 2020. He began producing music by using Vocaloid software Hatsune Miku during his hospital treatment for peptic ulcer disease. He uploaded his first song, "Sentensei Assault Girl", on Niconico in 2018 and gained popularity with "Last Resort" a year later. He released his debut EP, Ghost City Tokyo, in December 2019. Lilas Ikuta, who adopted the stage name Ikura for Yoasobi, started performing guitar on the streets and small venues at the age of 14, and uploading her music and covers via YouTube. In 2016, she participated in Sony Music Entertainment Japan's artist training course, the Lesson, and created her demo, 15 no Omoi. Later, Ikuta joined the cover group Plusonica until 2021, and issued her first two EPs: Rerise (2018) and Jukebox (2019) via independent label After School.
In 2019, Yohei Yashiro, a founder of Monogatary.com, a social media platform for creative writing and illustration owned by SMEJ, presented the idea of a project to produce songs inspired by selected story submissions published on the website as a prize to authors instead of a book or anime adaptation, though not all were successful. Yashiro enlisted Shuya Yamamoto, who handled SMEJ's artists at that time, shortly after their first meeting at a party. In the mid-year, Ayase received an offer from Yashiro and Yamamoto to produce songs for the project. During the vocalist discussion, he discovered Ikura covering Aimyon's "Kimi wa Rock o Kikanai" on Instagram. He contacted her directly to persuade her to form a duo. Yoasobi announced their debut via a teaser video on October 1, 2019, marking their anniversary. Originally planned for making few songs as a trial run, the duo first produced the two songs based on two short stories, which won the Sony Music Award at Monogatary.com's novel contest, Monocon 2019, consisting of "Yoru ni Kakeru" from Mayo Hoshino's short story Thanatos no Yūwaku and "Ano Yume o Nazotte" from Sōta Ishiki's Yume no Shizuku to Hoshi no Hana.
A music video for "Yoru ni Kakeru" was uploaded on November 16, 2019, and accrued one million views on YouTube within a month. The song was subsequently released to digital music and streaming platforms the next month, on December 15, independently from SMEJ's labels and distributed by the Orchard. During the beginning of the COVID-19 pandemic in Japan in early 2020, "Yoru ni Kakeru" went viral on social media, as well as its The Home Take live performance by Ikura. Six months after its release, the song ascended to number one on the Oricon Combined Singles Chart, and the Billboard Japan Hot 100. It spent a total of six weeks atop the latter chart, of which three weeks were consecutive. Eventually, "Yoru ni Kakeru" finished 2020 as the year's number-one Japan Hot 100 song, making it the first-ever year-end chart topper with no physical release. The song won the Song of the Year at the 2020 MTV Video Music Awards Japan and the 2021 Space Shower Music Awards, and the Silver Prize at the 2023 JASRAC Awards.
Following their debut single, Yoasobi released "Ano Yume o Nazotte" on January 18, 2020. Four months later, "Halzion" was released on May 11 as part of Suntory's Immersive Song Project to advertise energy drink Zone. Sourced from Shunki Hashizume's Soredemo, Happy End, it was the duo's first collaboration with a professional novelist, whereas the first two were amateur writers. In the second half of the year, they continually released three more singles. "Tabun" was released on July 20 and was based on the short story of the same name by Shinano, which won the Yoasobi Contest Vol. 1. Used on Bourbon's Alfort Mini Chocolate commercial, "Gunjō", featuring uncredited chorus from Plusonica, was released on September 1. The song was sourced from the short story written by the brand's creative team Ao o Mikata ni, inspired by the manga series Blue Period. On December 18, the duo released the single "Haruka", a collaboration with screenwriter Osamu Suzuki for its based short story Tsuki Ōji.
On December 31, Yoasobi concluded 2020 at the year-end television special 71st NHK Kōhaku Uta Gassen with the debut live performance of "Yoru ni Kakeru" as a duo, along with the band members, filmed at Bookshelf Theater, Kadokawa Culture Museum in Tokorozawa. It made the duo the first-ever artist to perform at the TV special without any physical releases. All previously released singles were featured on the duo's debut EP The Book, released on January 6, 2021, expressing a theme of "reading CD" with binder package. It additionally included "Encore", based on Yoasobi Contest Vol. 1-winning Sekai no Owari to, Sayonara no Uta by Kanami Minakami and featured on Google Pixel 5 and Pixel 4a (5G) advertisement. The EP debuted at number two on the Oricon Albums Chart and the Billboard Japan Hot Albums. As of 2021, The Book has sold 150,000 CD and 100,000 digital sales, the latter making it the only album to reach the milestone that year, and was certified gold for the both by the RIAJ. The EP won Special Award at the CD Shop Awards.
2021: The Book 2
First announced in late 2020, Yoasobi recorded both the opening and ending themes for the second season of the Japanese anime series Beastars. Its opening theme, "Kaibutsu", was released on January 6, 2021, while its ending theme, "Yasashii Suisei", came on the 20th. Both songs were based on short stories written by the anime's writer Paru Itagaki—Jibun no Mune ni Jibun no Mimi o Oshi Atete and Shishiza Ryūseigun no Mama ni, respectively. The double A-side CD single of both tracks reached number two on the Oricon Singles Chart, and made "Kaibutsu" peaking at number two on the Japan Hot 100. "Kaibutsu" won four awards for Song of the Year (Japan) in both download and streaming categories at the 36th Japan Gold Disc Award, and ranked number five in Time 10 Best Songs of 2021, the only Japanese act to appear on the list. In support of The Book, the duo held their first livestream concert, Keep Out Theater, on February 14 at the construction site of former Shinjuku Milano-za (today Tokyu Kabukicho Tower) for 40,000 online audiences. The duo hosted their Tuesday slot of radio program All Night Nippon X from March 2021 to March 2022.
Yoasobi's song "Mō Sukoshi Dake", based on the Yoasobi Contest Vol.3 with Mezamashi TV-winning story Meguru by Chiharu, served as the 2021 theme for the morning show Mezamashi TV since April and was released on May 10. The duo's "Sangenshoku" was released on July 2, using as jingle for NTT Docomo's mobile network operator Ahamo commercial since February, based on scriptwriter Yūichirō Komikado's RGB. On August 9, they released "Loveletter", sourced from Hatsune's letter, "Ongaku-san e", which won Japan Post Service-owned radio show Sunday's Posts Letter Song Project. From September 9 to 13, the duo and Sony Park Exhibition held an exhibition, Semiconductors Create New Realities, at Ginza Sony Park, where their song "Taishō Roman" accompanied the event. The song was adapted from Natsumi's short story Taishō Romance, a winner of Yoasobi Contest Vol.2, and was released two days after the exhibition ended. The duo was in charge of a theme for Sustainable Development Goals (SDGs) children's television shows Hirogare! Irotoridori, "Tsubame", featuring vocal group Midories. The song was released on October 25, and based on Nana Ototsuki's short story Chiisana Tsubame no Ōkina Yume. In the same month, they appeared on YouTube Music's Artist Spotlight Stories.
Yoasobi released their second EP, The Book 2, on December 1, 2021. Alongside their all singles released that year, it included "Moshi mo Inochi ga Egaketara", a theme for and based on the 2021 play of the same name written and directed by Osamu Suzuki, performed in August and September 2021. The EP debuted at number two on the Oricon Albums Chart, and topped the Billboard Japan Hot Albums for the first time. It won Special Award at the CD Shop Awards. In support of The Book 2, Yoasobi held their first face-to-face one-off concert, Nice to Meet You, at Nippon Budokan on December 4 and 5, receiving 14,000 offline attendees, and starred on an episode of documentary program Jōnetsu Tairiku on December 12. The duo participated in the 72nd NHK Kōhaku Uta Gassen on December 31, where they performed "Gunjō" for the main show, featuring a symphony orchestra, and "Tsubame" as part of "Colorful Special Segment" with Midories and mascots from Hirogare! Irotoridori.