A blind hitokiri working under Takasugi, he aims to destroy everything in the world, much like his master. His swordsmanship is so advanced that he can strike down an opponent without them noticing him drawing his sword. However, during their first encounter, Nizou's sword was shattered by Gintoki. Later on, Nizou reappears, severely wounding both Katsura and Gintoki with the demonic blade known as 'Benizakura,' which transforms his arm and merges with it. The Benizakura behaves like a parasite, gradually taking control of Okada's body, turning him into a deranged monster. Due to the sword's influence, his body has undergone numerous modifications, including cybernetic enhancements across his entire upper torso. He is ultimately defeated by Gintoki. Though his ultimate fate remains unclear, it is presumed that he perished due to the effects of the Benizakura.
His name is loosely inspired by Okada Izō, a hitokiri from the Bakumatsu period.
