Mohji is the first mate of Buggy's crew. He is known for being quite pompous and sometimes silly, but he claims to have the ability to control any animal he desires. While he has proven this claim with his pet lion named Richie in some instances, others believe that Richie is more like another crew member than just a pet. Mohji prefers using Richie in battle rather than fighting himself due to his fast and agile nature as well as his skill with a whip. He is also responsible for burning things such as the pet-food shop and Going Merry.
In his first appearance, Mohji was sent by Buggy to capture Roronoa Zoro. However, Monkey D. Luffy got in his way, resulting in him being defeated after he burned down a pet-food shop belonging to a recently deceased man and his still-living dog. After Buggy's defeat, Mohji and Cabaji fought over leadership of the group. They were equally matched until Richie knocked them both unconscious while sleepwalking, taking over leadership himself. The pirates were later kidnapped by cannibals but were saved by Buggy, Alvida, Mohji, and Cabaji.
Mohji participated in the attack on Loguetown, where his job was to burn down the Straw-Hats' boat. However, he failed to do so as soon as it started raining. Nami and Usopp found him and Richie but as soon as Mohji sent Richie to attack, Usopp used an egg to distract the lion. The Marines arrived, and everyone was shot at. Mohji managed to dodge the bullets and escape with the rest of Buggy's group.
Mohji later reappeared with the crew in the Grand Line as they found Portgas D. Ace. He also appeared in a TV special featuring One Piece characters as ninjas, and was seen in several video games. Every time Mohji appears in an arc, his hairstyle changes. During the Buggy arc, he had teddy bear-shaped hair; during the Loguetown arc, he wore a pink helmet with bunny ears sticking out; and when the group made it into the Grand Line, his hair was styled like a lion's mane.