Kamen Rider Gotchard: What's That?! Houtaro and Rinne Switched Places!!

Houtaro and Rinne find themselves in each other's bodies. To reverse the situation and return to their own forms, they must complete a specific mission assigned by Inphoenix and Firemars. During this process, they receive assistance from Supana and Professor Minato, though both individuals exhibit unusual behavior. The story also introduces the character Kamen Rider Gotchard MarsPhoenix.

This Japanese action comedy blends science fiction elements in a short runtime of 17 minutes. Produced by Toei Video Company, the film was directed by Koichiro Hayama and written by Takahito Oonishi. The cast features Junsei Motojima as Houtaro Ichinose and Reiyo Matsumoto as Rinne Kudo, with Yasunari Fujibayashi appearing as Supana Kurogane and Rikuto Kumaki as Minato. Voice roles are provided by Rie Takahashi as X Wizard and Inphoenix, and Misato Fukuen as Hopper1. The film was released on April 3, 2024.