This guy is one of Crush Groove's (the band) first friends/rivals in the world of professional music. He introduces the band to Vibe and invites them to participate in the War of the Bands.

His name is Aaron and when he needs a musical weapon he uses a bullhorn.

Also, the other characters have names. Porcupine dude is Shades, and Bear guy is Barret. Their drummer is Nao. She'll pop up later.

I read Soul Eater before I came up with this guy. Could you tell?