Reche was part of Egoist with her former Stage Name "Chelly".

From May 25th to June 19th, 2011, Supercell held an audition to find two new guest singers for their group. From over 2000 candidates, Chelly (17) and Koeda (15) were selected to be supercell's new singers. She is a good friend of Koeda, the other guest singer. Chelly has a soft, unique, and a well balanced voice. It has been noted that Chelly loves to draw. And no one publicly knows what the singer actually look like.

As one of two new guest singers of Supercell, Chelly was assigned to provide vocals for the singing voice of Yuzuriha Inori, who is the vocalist of a fictional band named EGOIST and the female lead of the anime Guilty Crown'. Her first two singles, were featured as a part of the anime. 'Departures ~Anata ni okuru ai no uta~' was used as the ending theme of the first half of Guilty Crown, while 'The Everlasting Guilty Crown' was the opening for the second half of the show. 'Euterpe' became an insert song that serves as the signature song of the fictional band.

With the rising popularity of Chelly's vocal appearance in Guilty Crown, the band EGOIST continued to exist in the real world even after the anime. The singer's face remains a mystery as Chelly retains the persona of Inori. EGOIST got another anime feature in Psycho-Pass and provided the ending themes to it. 'Namae no nai Kaibutsu' was released as the anime first ending theme and 'All Alone With You' was the second ending theme song.

Because of her popularity, she was been chosen to perform in AFA (Anime Festival Asia) Singapore 2013 together with some well-known artists such as; LiSA, Aoi Eir, May'n, and more. She has released a new single for the AFA Singapore 2013 as EGOIST which is titled "Suki To Iwareta Hi" (好きと言われた日).

When Psycho-Pass 2 came into production, EGOIST had an appearance once again to create the ending theme 'Fallen'.

On the 20 May, 2015, Supercell was hired to compose music for the game Bravely Second. Chelly's vocals were used; this time, however, as a featuring artist of Supercell instead of EGOIST. She sung "Great Distance" which was used as the opening theme and "Last Song" for the ending theme.

Chelly returns as EGOIST with the production of the single 'RELOADED', which features three songs as themes for three different movies.

In 2016, EGOIST were featured in the anime Koutetsujou no Kabaneri with the opening theme "Koutetsujou no Kabaneri" and the ending theme "ninelie" in collaboration with the artist Aimer.

In 2017 she released a single titled "Eiyuu Unmei no Uta" under EGOIST, which was featured as the first opening theme for the anime Fate/Apocrypha.

In August 2023, it was announced that EGOIST would disband after two final concerts, Chelly has performed and will continue as a solo artist under the name Reche.