The new Sgt. Frog film celebrating the franchise's 20th anniversary is bringing together a surprisingly huge lineup of guest cast members. The official website announced the additions on Tuesday, revealing voice actors Tomokazu Seki, Natsuki Hanae, and Kōichi Yamadera among the roles, alongside members from idol groups JO1, FANTASTICS, Hinatazaka46, and SixTONES.

Jesse from SixTONES is pulling double duty, voicing brothers Aruru and Deruru—new characters from the planet Keron with connections to Sgt. Frog's unit. Singer ano and comedian Soshina, who're performing the film's opening theme "Mata Kaettekita KERO! to MARCH," also appear on screen. Ano performs a researcher robot while Soshina plays a man in Shibuya.

The film, titled New Sgt. Frog the Movie: The Earth Is in Mortal Peril as Soon as We Come Back!, opens in Japan on June 26. Director Yūichi Fukuda (live-action Gintama, Saint Young Men) supervised the project and penned the script, with Fumitoshi Oizaki directing at Bandai Namco Pictures. Character design comes from Satoshi Koike (Etotama, Soul Eater Not!).

The movie keeps the franchise's original voice cast, making it distinct from the brand-new TV series arriving this fall. That upcoming show, titled Keroro Gunsō ☆, will feature a completely fresh cast when it premieres fall 2026.

For those unfamiliar with the franchise, Keroro (Sergeant Frog) leads an alien invasion force stationed on Earth. After his troops scatter and the mission stalls, the would-be conqueror ends up doing housework and battling a karaoke addiction instead of planning world domination. The original anime ran through the late 2000s, and Crunchyroll added it to its library in 2021.

With both a theatrical film and a new TV series in the pipeline, Sgt. Frog's 20th anniversary is shaping up to be a major moment for the comedy-heavy franchise. Whether the idol cameos and expanded guest cast will appeal to longtime fans or introduce the series to new audiences remains to be seen—but the scale of this celebration suggests Bandai Namco is betting big on Keroro's continued relevance.