Renjiro Yamaoka was Kazan Yamaoka's father. He, like his son, was a powerful Samurai; however, Kazan wanted to surpass his father in terms of reputation. During the beginning of Kazan's pilgrimage to get rid of the imposter Samurai, his father tried to steer him away from proceeding with his plan. Kazan ignored his advice, and continued on.
On Kazan's way to kill the lord for the embarrassment the lord had inflicted upon him, he unknowingly came across his father dressed in full Samurai armor and blocking his path, and proceeded to attack him, crushing his skull in with his Kanabō.