What is the subject and style of the song "Superboy and the Invisible Girl"? Who sings it?

In Act 1, Scene 7, as Henry offers Natalie some marijuana, music starts (a mid-tempo, folk/rock song, "Superboy and the Invisible Girl"), and Natalie vents her anger at being the child always disregarded in favor of her parents' concern about her dead brother. At one point, Diana appears and comments that she loves her daughter as much as she can.