Izou was a master swordsman and a member of Wild Hunt.
Izou was a tall man with black hair worn in a top ponytail; his clothing resembled that of a samurai. His eyes were shown to have black sclerae and red irides, but he usually kept them closed. He was often seen with a twig in his mouth. He carried his sword Kousetsu tied to his belt.
Izou was a calm, stoic man with immense bloodlust. He claimed that he needs to allow Kousetsu to "drink blood" regularly. He loved the Empire for allowing him to have as many fights as he wanted. Unlike the most of his fellow Wild Hunt members, he did not have an obsession with sexual abuse. He was also shown to honor foes that he's faced with a strong will, such as Lubbock.
Izou was recruited by Syura during his travels around the different kingdoms and nations in order to serve as a member of his newly formed group, Wild Hunt.
When Wild Hunt committed various crimes throughout the capital, Izou didn't do much such as participating their mass rape or torture as he was only interested in killing his opponents to "feed" Kousetsu. And did nothing but kill the people standing in Syura's way.
He was shown to patrol the imperial palace and cut down Lubbock, who tried to escape from its prison, killing him. However, he had said that Lubbock had earned his respect for his strong determination to live.
Later he was seen together with Dorothea, preparing to go out with Cosmina who is now merged with a Danger Beast. After attacking several Revolutionary Army outpost and slaughtering every person there, the trio was confronted by Akame, Leone and Tatsumi of Night Raid. Izou fought Akame and, despite predicting her moves, was eventually cut down by Akame. Before dying, he praised Akame's skills and offered her to take Kousetsu, but she refused to do so.
Izou was seen to be a master swordsman who excels at handling his sword: Kōsetsu (江雪). The manner in which he used it greatly resembles Iaido, a real-life Japanese style of sword-fighting.
After losing two of the Wild Hunt members, Syura claimed that having Izou would make up for these losses.