A mysterious alchemist studies and experiments to create "living creatures" called Chemies. Unfortunately, the cards holding them that should have been kept secret are accidentally unleashed on the world. High school student Houtarou Ichinose is tasked to retrieve all the Chemies released around the world. Using the Grasshopper Chemy, Hopper-1, and the Steam Locomotive Chemy, Steamliner, he transforms into Kamen Rider Gotchard!