Egoist (stylized as EGOIST) is a Japanese pop music solo act consisting of vocalist Chelly produced by songwriter Ryo of Supercell. Originally formed to produce theme music for the 2011 anime television series Guilty Crown, the group continued to produce music after the end of the series. Egoist's debut album Extra terrestrial Biological Entities was released in September 2012.
In 2011, Ryo of Supercell was tasked with composing theme music for the anime television series Guilty Crown. That year, Supercell held auditions from May 25 to June 19 for the vocalist on the band's third studio album Zigaexperientia (2013), and Ryo was also searching for the vocalist of Egoist, a fictional band featured in Guilty Crown. Out of about 2,000 candidates, then 17-year-old female singer Chelly was chosen to sing under the persona of the band's vocalist Inori Yuzuriha. Egoist's debut single "Departures (Anata ni Okuru Ai no Uta)" was released on November 30, 2011; the song was used as Guilty Crown's first ending theme. Egoist's second single is "The Everlasting Guilty Crown" released on March 7, 2012; the song was used as Guilty Crown's second opening theme. Included on Egoist's first two singles are remixes of the title songs by Boom Boom Satellites. Egoist's debut album Extra terrestrial Biological Entities was released on September 19, 2012.
Egoist's third single "Namae no Nai Kaibutsu" (名前のない怪物) was released on December 5, 2012; the song is used as the first ending theme to the 2012 anime series Psycho-Pass. Egoist's fourth single "All Alone With You" was released on March 6, 2013; the song is used as the second ending theme to Psycho-Pass. Egoist released the digital single "Suki to Iwareta Hi" (好きと言われた日) on November 6, 2013.