Higuma was a man who was used to getting his own way. He walked about as though he owned the world and was prepared to kill if need be. If anyone resisted him, he would threaten them with his status as a criminal and a killer. In truth he was a coward and proved this twice; when his men were wiped out and when he faced the Sea King.
During the childhood of Monkey D. Luffy (covered in the first chapter of the manga and a flashback early on in the anime), Higuma was the leader of a band of mountain bandits. The band swept into the town where Luffy lived and demanded grog, only to find that the last of it had been purchased by Red-Haired Shanks and his crew. Higuma personally insulted Shanks before storming out of the town; while Shanks laughed it off, Luffy was furious that Higuma had disrespected his hero.
Shortly afterward, while Shanks's crew was out on a voyage, Higuma and his band returned to town. While drinking at the same pub where they'd caused trouble before, Higuma insulted Shanks behind his back - and in earshot of Luffy. Infuriated, Luffy attacked the bandit, only to be thrown down and beaten by the entire group of bandits. Undaunted, Luffy insulted Higuma, and the bandit tried to kill him.He was interrupted by the return of Shanks and his crew. Seeing what the bandits were doing to Luffy, the pirates decided to interfere and save Luffy. After Shanks tried to approach their leader one of Higuma's men threatened to shoot Shanks but instead was himself shot dead by Lucky Roo. After the death of one man, Higuma became furious and ordered all his men to attack, only to be shocked by Benn Beckman, who defeated them all by himself. Turning coward, Higuma threw a smoke bomb and in the cover fled with Luffy as a hostage.
He set out to sea, reasoning that given his attitude towards pirates, no one would look for him on the water. He then kicked Luffy out to sea, knowing the boy couldn't swim due to the Devil Fruit curse.
Immediately afterward, however, a Sea King rose from the waters. Higuma, terrified, could do nothing as the creature destroyed his boat and devoured the bandit with one bite.