|The captain of the Fourteenth Unit of the Holy Harmonia Kingdom's Southern Frontier Defense Force. Geddoe is his professional rival.
— Duke's profile
Duke serves as the leader of the 14th Unit of the Harmonian Southern Frontier Defense Force. He is a talented leader and fighter, though his pride occasionally obscures his judgement, such as his one-sided rivalry with Geddoe, leader of the SFDF's 12th Unit.
Initially during the War of the Champions, Duke and his unit worked under the Masked Man and this role would lead to even more conflicts between him and Geddoe, usually with his team coming out on the losing end, fueling the rivalry still further. However, after Luc's attack on Geddoe at Mt. Senai and understanding what the realization of Luc's plans would mean for both the Grassland and the SFDF, Duke would help Geddoe's unit escape and would fight alongside the Fire Bringer from them on.
Still, his rivalry with Geddoe never abated and the two were never going to get along well. Following the war, Duke married Elaine and headed south on a new mission, hoping for a rematch against Geddoe in the future.