In this special, Houtaro and Rinne swapped bodies! In order to return to their original bodies, they need to a complete mission given to them by Firemars and Inphoenix! To help them, both Professor Minato and Supana are acting differently?! The special will also feature the debut of Kamen Rider Gotchard MarsPhoenix!

"Fight! Gotchard Marsphoenix!!"