Hotaru holds the title of "absolute idol," reigning supreme in both popularity and skill within her universe. Her Japanese name translates to "firefly." She stands as the ultimate inspiration for countless idols, including every member of the group TINGS, who all strive to match her success. Her influence profoundly impacted Haru Nabatame, the protagonist and leader of TINGS; witnessing Hotaru's concert sparked Haru's decision to become an idol.

Hotaru shares a close, informal friendship with Naoki Hinase, TINGS' manager. He uses the nickname "Kei" for her, and their interactions feature frequent playful teasing; Hotaru often jokingly tells him to "commit seppuku" during phone calls, indicating a longstanding, comfortable rapport.

A key revelation in the anime's final episode discloses that Hotaru was the originator of the "Shine Post" concept, which she entrusted to Haru. This revelation also clarifies that Haru already knew of Naoki beforehand through her connection with Hotaru. Hotaru's role centers on being an aspirational figure and a narrative catalyst; specific details about her personal background, character development across seasons, or appearances in expanded media like movies, OVAs, or spin-offs are not provided.