Runa is a high school student from File 11, "The Whispered Voice Requires Self-Responsibility." She got her start as a streamer back in middle school, though things never really took off until she stumbled onto a weird video called "Blue World." After watching it, something changed—she developed this siren-like voice that lets her command people to do whatever she says. It's a pretty broken ability, honestly, and she's used it to build up a following as a narrator of "self-responsibility ghost stories," basically creepypasta-style content where viewers are on their own for dealing with the fallout.
Sorawo mentions that Migiwa once told her Runa's real name, but she's since forgotten it.
Content compiled by AnimeList.moe from publicly available sources.
