Benkei is a purist from the Wushanko Isles who is considered an extremist even by Purist standards. He is the nemesis of Sojobo, and and is involved in The Tengu's story voyages in the Player-owned port minigame, in addition to the Guardians of the World trio voyages.
During the Tengu's story, it is discovered that he aided an Oni warlord known as Obanak in terrorizing Ai Jei in exchange for weapons, and then raised the spirits of deceased sky orphans on the Teardrop Islands in order to discover the location of a powerful relic known as the Fenghuang Feathers, which allow the user the power of flight and the ability to control the spirits of sky orphans. With the relic, he planned to raise an army to wipe out the seasingers of Wushanko.
After discovering that the feathers were located in Haka-su, a sky orphan temple near The Pearl Fortress, he took them but was soon after attacked by Sojobo and Shanao, who defeated him and took the feather he had. They spared him, and he revealed that he was in the employ of another man known as Kakashi, who had taken the rest of the feathers.
Owing a life debt to Sojobo and Shanao, he acted as a spy for them, and revealed that his employer was planning an attacking on the seasingers of Paradise. By the time the duo got there, he had already killed a large number of sea creatures, but Benkei was able to steal the remaining Fenghuang Feathers back from Kakashi, ending his attack at the last moment. Kakashi was able to escape, so Benkei remained in Kakashi's service in order to help the Tengu duo in future.
Some time later, Benkei informed Sojobo that Kakashi was building a weapon, which proved to be crucial information about Kakashi's plans. Later, Honovi - one of Sojobo's allies - went to meet up with Benkei on the Bladewing Crag to learn if he had any further information about Kakashi's plans, but she arrived only to find his corpse, which she theorized to have been the handiwork of her brother.
- Benkei is named after Musashibou Benkei, a famous Japanese warrior.