Mori Calliope's fictional lore describes her as the "Grim Reaper's first apprentice" who, due to slow business, had to start a career as a VTuber and collect souls.

[8] 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.

Katie Gill of Anime Feminist described her profanity-laden rap music as an exception to the widespread use of Japanese idol themes within Hololive.

[15] Teddy Cambosa of Anime Corner said that her "style of rapping comes in line with the rise of other large VTubers that are now leaning towards a more Western preference instead of the Japanese idol grassroots".

[16] In an August 2022 Crunchyroll News interview, when asked which music was the most influential to her, Mori explained that her interest in rapping was first sparked by Japanese hip hop, citing the genre's unique style and intensity.

[20][21] In June 2022, she expressed regret, admitting she hadn't realized how big Hololive had become at the time of the stream.

[26] In March 2024, Mori and Warner Bros. announced that she would be singing the ending theme for the anime Suicide Squad Isekai, titled "Go-Getters".