藤岡幹大 Silent night & Metal Song For Practice (Mikio Fujioka) at Kemper Seminar 2017 

I was in the 2nd row in front of Fujioka-sensei on 23/12/2017. I remember Fujioka-sensei told us that's a kind of expression pedal. He used the pedal with the harmonized setting by the KEMPER.