Benkei is a traveling monk and sword collector who had obtained 999 swords through battles he won himself. While searching for a fitting 1,000th sword he came to Sei-an City after hearing of a 'living sword' said to swim freely in its waters. He lowered the jigsaw bridge leading into the aristocratic quarters of Sei-an City because it made a great fishing spot but it cut off the citizen’s access to the priestess Roa. Benkei gives his word that once he has caught the 'living sword' he’ll raise the bridge. Upon catching the 'living sword' Benkei is disappointed to find it was just a cutlass fish but keeps his word and raises the bridge. Afterwards Benkei decides his life of sword collecting is a hollow one and instead pursues a life as a fisherman.
In Ōkamiden Benkei challenges Kurrow for his flute knowing it is a light-saber like sword but is talked out of it by a shipmate who tells Benkei of the 'living sword' that swims in the waters of Sei-an City.
Benkei is based on the historical character "Saitō Musashibō Benkei" who was the main companion to a Robin Hood like character called "Minamoto no Yoshitsune" (known as Ushiwakamaru in his childhood) whose character also appears in Ōkami as Waka.