Izou Okada, also known as the 'Human Slayer,' is a Servant in the mobile game Fate/Grand Order. He is a famous historical figure from the late Edo period of Japan, known for his exceptional swordsmanship and his role as an assassin during the Bakumatsu era. In Fate/Grand Order, Izou is portrayed as a Berserker class Servant with a strong sense of pride in his skill with the blade. Despite his rough demeanor, he is a deeply reflective individual who struggles with his identity and the weight of his past actions.