Gaou is one of the main characters in the 4th volume of the series. His face is hideously deformed and has had only one arm since infancy. He is a mass murderer who bears an incredible hatred toward all of the world.
Gaou is one of the many incarnations of Saruta

Gaou is eventually redeemed after becoming a traveling hermit, and is discovered to have tremendous talent as an artisan

Gaou's last arm is cut off because of Akemaru