Okada Nizou (岡田 似蔵), also known as Nizou the Butcher, or Manslayer Nizou (Hito Kiri Nizou) was a blind assassin and a master of Iai jutsu, which are techniques for drawing a sword. He was a member of the Kiheitai, an extremist Joui faction bent on causing world destruction, and would become fused with the Benizakura bio-mechanical sword, which would ultimately take over his body completely and lead to his defeat. He was the main antagonist of the Infant Strife Arc and Benizakura Arc.
He had dark gray hair that was combed backwards, with sideburns. Being blind, he wore glasses with orange lenses and normally had his eyes closed. His usual attire consisted of a green kimono with dark green linings and dark green/black pants. When it came to weapons, he used a shirasaya sword during the Baby Grandson Chapter, but would later wield the bright-shining purple Benizakura bio-mechanical sword, which would alter his appearance altogether, making him a great deal larger, with tubes and hoses extending from his arms and torso.
Nizou was a ruthless murderer and a criminal. Nizou himself said that after living a long time in darkness, he perceived a light too faint for the eyes to see. He continued that he didn't recall when he learned that the light radiated from human beings, and that it shined brightest, like a brilliant flower of light, just before they died. He also commented that there are a few who shine just as bright when they're alive, Sakata Gintoki and Takasugi Shinsuke being two of them. He also seemed to have high opinion of his skills, as he stated to Gintoki that if he would have been at Takasugi's side during Joui war instead of Gintoki, history may have taken different turn.
Strength & Abilites
Even though he was blind, his other senses seemed very sharp. He carried around a nose refreshner with him, since he depended on his sense of smell.
When it came to weapons, he used a shirasaya sword during the Baby Grandson Chapter. However Gintoki broke his sword.
But would later be implanted with the bright-shining purple Benizakura bio-mechanical sword, which would alter his appearance altogether, making him a great deal larger, with tubes and hoses extending from his arms and torso.
Story
Infant Strife Arc
Okada Nizou was first introduced in the Baby Grandson chapter, where he would cross swords with Sakata Gintoki, as the hired hand of Hashida Kahei to take back his baby grandson. However, Kahei's plan failed and Nizou was defeated by Gintoki. On the other hand, Kahei was still allowed to see his grandson by his daughter-in-law, who forgave him.
Benizakura Arc
Nizou would make a another, and much larger appearance in the Benizakura chapter, where he would wield the Benizakura bio-mechanical sword. With the Benizakura sword, he presumably killed Katsura Kotarou, who was later revealed to have survived their encounter. He also fought Sakata Gintoki for a second and a third time. The second time, he taunted Gintoki by making fun of Katsura's hair and claiming that he had killed him. Gintoki refused to believe this and engaged him in battle. He badly injured Gintoki, who was unaware of Benizakura's properties and abilities at the time.
Later on, Nizou destroyed two jouishishi air ships with his infused Benizakura while riding on an air bike. The third fight with Gintoki was their final and longest, which ended after the Benizakura had completely taken over Nizou's body, turning him into a rabid monster unable to distinguish between friend and foe. Gintoki put an end to it with a sword made by Murata Tetsuko, breaking both the Benizakura and his own sword. All of the tubes and hoses on Nizou's body disappeared and he caved in. However, it's uncertain if he only reverted back to his old self, or if he passed away right there and then, as Yamazaki Sagaru later reported that Nizou's body was never found. He has not made any other appearances after the Benizakura story arc.
Based on Okada Izo, who, like Kawakami Gensai, was also known as one of the four assassins.
Nizou's image on the wall to the left in Episode 152
In Kintama, a spoof of Gintama, Yorozuya Gin-chan became Yorozuya Shin-chan, headed by Takasugi Shinsuke with Takechi Henpeita and Kijima Matako as members. Nizou's photo was seen hanging on the wall next to what used to be Gintoki's table in a short scene which was briefly shown in the OP sequence of Episode 152 of the Gintama anime.
