M!LK's Shunta Sono is stepping into the Kamen Rider universe as a villain. The idol will play Shuma Kumon, a government official hiding a dark secret, in the upcoming film Kamen Rider Zetts releasing July 24, 2026.

Kumon appears as a respectable elite who serves as National Public Safety Commission chairman, but he's actually the series' primary threat—a reality-warping villain who transforms into Kamen Rider Mugen. The role plays to Sono's strengths: he's trained in swordplay and will wield a sword during action sequences, marking his first major stunt fight choreography.

"I've admired Kamen Rider since childhood," Sono said in a statement. "Getting to transform into one, even as a dark hero, is incredibly exciting." He emphasized working closely with the director on the transformation pose itself.

The film arrives as a double feature alongside Super Space Sheriff Gavan Infinity, billed as the summer 2026 dual hero event. M!LK fans will recognize this isn't the group's first Kamen Rider appearance—bandmate Jotaro Yamanaka appeared in Kamen Rider Gachard in 2023, and Sono credits him for offering acting advice throughout this project.

"The entire M!LK family has been supporting me," Sono explained. He underwent proper sword training for the role and promises the transformation sequence received special attention from the filmmaking team.

The Kamen Rider Zetts TV series airs Sundays on TV Asahi, following protagonist Maku Yorozu as he battles nightmare creatures using a chest-mounted transformation belt. The film expands that world with high-stakes action and cinematic production values.

Sono joins M!LK during a career peak for the group. Their 2025 single "Iijan" generated 2.7 billion social media plays and earned them a first NHK Kohaku Uta Gassen appearance. Their October 2025 release "Sukisugite Metsu" surpassed 3 billion social plays and 100 million streams.

The Kamen Rider Zetts & Super Space Sheriff Gaban Infinity double feature opens July 24.