[3][4] Her YouTube activity consists primarily of live streaming herself singing karaoke, playing video games, talking to her fans, or collaborating with other talents.

[8] Hoshimachi Suisei created her YouTube channel on 18 March 2018[9][10] and revealed her initial character design and model, illustrated and rigged by herself, on Twitter that same day.

[14] She released her first original song, "Comet", on 22 November 2018,[15] and her second, "Tenkyū, Suisei wa Yoru o Mataide" (天球、彗星は夜を跨いで), on 22 March 2019, both as YouTube music videos.

On 17 March 2020, her number of jiànzhǎng (舰长, or "captains", viewers who donate over 198 renminbi to a particular streamer every month), surpassed 1,000, over 700 of whom joined during the aforementioned concert.

In the summer of 2021, Hoshimachi announced a series of three back-to-back monthly digital extended play releases, starting with "Bluerose / Comet" on 25 June.

[43] On 21 October 2021, Hoshimachi performed her first paid concert, "STELLAR into the GALAXY", at Tokyo's Toyosu PIT with streaming on SPWN,[44][45] featuring NIJISANJI VTuber Inui Toko and fellow Hololive member AZKi as guests.

[51][52] It was released on 27 July 2022,[53][54] and the group performed in a SPWN-streamed concert mixing virtual and real elements and featuring a live band[55] on 20 August.

[69] She announced each concert would feature a different guest: Hoshimatic Project (a hololive VTuber idol unit organised by Hoshimachi herself)[70] on 14 November at Saitama Super Arena, KAF on 10 December at Ookini Arena Maishima, and Shiranui Constructions (another hololive sub-unit Hoshimachi is a member of)[71] on 28 December at Fukuoka Sunpalace.

[73] On 8 October 2024, it was announced Hoshimachi would perform at the final day of Countdown Japan 24/25, alongside acts including Zutomayo and Sumika.

[74] On 11 October 2024, Hoshimachi announced that she would be appearing at YouTube Fanfest 2024 alongside acts including Hajime Syacho and Hikakin.

[8] Hoshimachi's YouTube activity consists primarily of live streaming herself singing, playing video games, talking to her fans, or collaborating with other talents.

[5][6] Her work as a music artist includes performing in live concerts, singing and writing lyrics for her own singles and albums, and contributing as the singer for Midnight Grand Orchestra.

She has had her music appear and been represented by an in-game character in video games including Chunithm[77] and THE iDOLM@STER Cinderella Girls Starlight Stage.

[80] On 22 November 2022, it was announced she would be releasing the official series theme song for the game DYSCHRONIA: Chronos Alternate, "7days", which was also featured on her album Still Still Stellar.

[88] Hoshimachi also appeared on other radio shows during and after the run of Parallel Scramble (which ended broadcasting after 1 October 2023),[89] including SCHOOL OF LOCK!