Aimee Mann was a North American singer, songwriter and rock guitarist.
Aimee played the song "This Is How It Goes" at the Bronze around the time Spike had been brainwashed by the First Evil to serve as its sleeper agent. She was aware of the existence of vampires and of Sunnydale's reputation. She witnessed the death of the vampire Charlotte, which caused her to stop singing for a couple of seconds, only to resume after the initial shock passed.
Behind the Scenes
She was portrayed by herself.
Unlike every other non-fictional musical guest in Buffy the Vampire Slayer, Aimee Mann had a speaking role in the episode, thus she can be considered a character within the fictional Buffyverse.
She knows about the existence of vampires.
She played the songs This is How it Goes and Pavlov's Bell from her 2002 recording release, Lost in Space.