Mori Calliope made her debut along with the other members of Hololive English Myth on 12 September 2020. She released her first single "Cursed Night" on 2 November 2020. This was followed on 4 April 2021 with another EP,
Your Mori.; it charted at #35 at the
Oricon Albums Chart. In April 2022, Mori announced that she had signed with
EMI Records, and that she would mark her major-label debut with her third EP,
Shinigami Note. Released on 20 July 2022,
Shinigami Note charted at #9 at the Oricon Albums Chart. On 21 July 2022, Mori's first solo concert,
New Underworld Order, was held at Toyosu Pit in Tokyo. On 11 October 2022, it was announced that she would release her debut album
Sinderella on 16 December; the album's themes include the
seven deadly sins and personal guilt. It charted at #28 at the Oricon Albums Chart. In July 2023, she released "Future Island", a song commemorating Volume 106 of
One Piece. On 18 August 2023, she released another EP,
Jigoku 6; it charted at #16 on the Oricon Albums Chart. In December 2023, she won Best Music Vtuber at the
2023 Vtuber Awards. In March 2024, Mori and
Warner Bros. Entertainment announced that she would be singing the ending theme for the anime
Suicide Squad Isekai, titled "
Go-Getters". In May 2024, it was announced that she would release her second major-label album,
Phantomime, on 16 August. In October 2025, Mori announced that she would perform the second opening theme in
Gachiakuta, titled "Let's Just Crash". In November 2025, it was announced that Mori would release her third major-label album,
Disasterpiece, on 6 February 2026. In addition to music, Mori does video game livestreams on her channel. In a December 2020 livestream, she spent at least 90 minutes asking video game developer
Atlus to allow her to stream one of their games,
Persona 3 (there is no
fair use doctrine in
Japanese copyright law, so VTubers often request permission from developers to livestream their games), which Petrit Baillet of
Dot Esports described as "a famous part of her ongoing streaming career". In June 2022, she expressed regret, admitting she hadn't realized how big
Hololive had become at the time of the stream. She has also appeared at
Anime Festival Asia as a musical guest twice: in 2022 and 2023. In November 2023, she appeared at
Anime NYC 2023 as a guest. In December 2023, she appeared at
Anime Frontier 2023 as a guest. ==Artistry==