He seems like a pit percussion guy to me. I bet he jams out on the hammer and brake every once and a while.
Maybe the flute, and he was also Madotsuki's flute teacher. Although, her flute teacher could have also been O-man.
But, but… He has no mouth, how can he play the flute?
HE WAS JAMMIN ON THE GUITAR.
HE IS THE FOUNDER OF DJENT