Duncan is a Marine stationed at the Marines' Tongari Island branch. He appears in Piece Trail: The Adventurer and the Amazing Spring.
Duncan is an average-sized man with short black hair. He wears a standard Marine uniform of a white sleeveless shirt, a white undershirt, a blue neckerchief, blue pants, black boots, and a white cap that says "MARINE" on the front.
Duncan is usually kind, but he is strict about rules.
Piece Trail: The Adventurers and the Amazing Spring
Duncan was recently stationed on Tongari Island. He advises the visitors of Tongari Island on how to participate in the Live Action Role Playing Game. He is involved in one of the game's endings alongside Eric.
- One Piece Live Shows - Piece Trail: The Adventurers and the Amazing Spring, Duncan advises visitors during the Live Action Role Playing Game.
- Duncan's personality is detailed on the official Tokyo One Piece Tower Twitter account.