Metal breath is a heavy metal band made up of 3 guys. Their names are Roadkill, Carnivore, and Scar Tissue. They are very loud, obnoxious, and rowdy. Kaz discovered them, and put them on tour with Ami and Yumi for 6 months.
On their first day, Carnivore played Yumi's guitar, Scar Tissue dived in the girl's hot tub and watched their TV while eating chips and Roadkill barged into the girls' fridge for food and put his head in Ami's cotton candy machine so he would have cotton candy hair, which Carnivore and Scar Tissue ate a bit of.
Metal Breath also stole the girls's audience, seeing as they requested Metal Breath and booed at Ami and Yumi when they tried to perform. After that, Ami and Yumi tried to sleep, but Metal Breath threw a party, which forced the girls to sleep on top of the bus. They wake up, only to find that the bus has been vandalized by the guys. Ami and Yumi then decided to gave them a makeover, which made them look like pop stars.
- Somehow, prior to the events of House Unkeeping, Metal Breath returned to their original looks.