Kiyoharu, from Japan. Special guest with Boris. Incredible vocalist!
This is only about the last half of their set. I spent 40 minutes stuck in the merch line, so I couldn't catch it all. Sorry :-(
Update: I've also made a seperate video of Kiyoharu performing with Boris during their set. Absolutely incredible!
https://youtu.be/1gW9dV1jNR0