One-Man is a big and burly man with brown hair that is put in a long ponytail sticking up, as well as a mustache and beard. Most of his chest is exposed, and he has a dragon tattoo on it. He wears part of a brown and white jacket at the bottom of his chest, brown pants, shoes, large sleeves and gloves on his forearms, and metal plates on his shoulders.
One-Man cares little for his subordinates and will refuse to help them out if he feels that they have outlived their usefulness. He is also prone to being petty and spiteful to them if they do something that negatively impacts him, as he left John to die for exposing his involvement in a raid, and was willing to attack people who supported him as well.
One-Man and the Amber Pirates orchestrated an attack on the Amber Harbor and Sapphire Town to find the treasure on Jail Island. One-Man's subordinate John was injured in the raid, and One-Man decided to leave him for dead out of anger. When Monkey D. Luffy, Tony Tony Chopper, and Jeanne came to help John, One-Man got angry at them and prepared to fight. He and his men battled Luffy, but were quickly defeated.