Saburo Kazeta is the leader of the Monster League and a major antagonist in Kamen Rider × Kamen Rider Wizard & Fourze: Movie War Ultimatum, serving as the secondary antagonist of Fourze's half. He has the power to assume a larvae armored fighting form called Sanagiman and later a moth-themed form called Inazuman. He is based on the heroic Inazuman from the manga and TV series of the same name by Shotaro Ishinomori.
Saburo and his friends Rumi, Chikao and Daita were all kidnapped by the Akumaizer due to their statuses as Gates and used to increase despair among humans in order to power the Akumaizer's monster plant.
Due to this experience, Saburo and his comrades turned bitter and evil. Years later, when they were attending Amanogawa High School, the four formed the Monster League to subjugate humanity and claim the Earth for neo-humans, receiving backing from Kageto Banba. During a class session, Saburo appears and announces himself as leader of the Monster League. He is soon confronted by Gentaro Kisaragi and assumes his Sanagiman to fight Gentaro as Kamen Rider Fourze. After receiving a Zeeber from Kageto, Saburo manages to fight off Fourze with his psychic powers, but before he can defeat him, Fourze is saved by Meteor and the two retreat.
Later, Gentaro and the Kamen Rider Club infiltrate the Monster League's base and reveal to them that Kageto is only using them and plans to sell them on the black market. His true plans exposed, Kageto becomes the Hercules Zodiarts and summons Stardust Ninja Dustards to cover his escape. As Gentaro pursues Kageto, Saburo appears to confront him once again, revealing his horrible childhood to the Kamen Rider. Gentaro then untransforms, and, as the ultimate sign of trust, throws his Fourze Driver into a furnace, finally causing Saburo to understand what it means to be a hero. Saburo then turns against Kageto and evolves into a much stronger form, Inazuman, which he uses to defeat the Hercules Zodiarts.