Crocus is a doctor and the caretaker of the whale Laboon as well as the overseer of the Twin Cape Lighthouse that guides ships coming down from Reverse Mountain into the Grand Line.

Though he was a lighthouse keeper for most of his life, he spent three years as a doctor serving as a part of Gol D. Roger's crew. According to Silvers Rayleigh, he was the best doctor in the world at the time he joined the Roger Pirates, and the only one able to relieve Roger's disease.

He is an ally during the Reverse Mountain Arc and provides the Log Pose used by the Straw Hat Pirates for the first half of the Grand Line.