Houtaro Ichinose and his friends continue their search for the Chemies. They accidentally encounter Ace Ukiyo and his friends, joining their fight with the Jyamato, who have appeared again. This is when the "Strongest Level 10 Chemy", X Wizard, suddenly appears and uses its magical powers to transform Keiwa Sakurai and the others into Chemies! At the same time, as many as five "Strongest Level 10 Chemies" and the Geats Chemy, which looks similar to Kamen Rider Geats, appear too! In order to break the spells, Houtaro, Ace and the others form into teams and take on the "Strongest Chemy Capture Game"!

What is the truth hidden in this mysterious game? What is the secret behind Geats Chemy's appearance? Will Kamen Rider Gotchard and Kamen Rider Geats be able to overcome the challenges waiting ahead and win the game?