After being pulled through a door, Shoma finds himself in a peaceful world where Dark Treats do not exist?! In this world, Hapipare still exist, but a young man named Taorin who has Gavv works there. Taorin has no memory of his past, and Shoma decides to help him recover his memories. Meanwhile, a man named Caries begins indiscriminately attacking the town, and the peaceful world is transformed! The two struggle to restore peace and arrive at a huge Candy House. The two are on the verge of grasping something, but Caries transforms with an unknown Gochizo and corners Shoma and the others! What is the soruce of the overwhelming power that this most terrifying enemy has obtained?! What are Taorin's lost memories?!

Granute, secret lifeforms, kidnap humans for "Dark Market Snacks." Shoma, from another world, transforms with Gochizo, a sweet-eating monster, into Kamen Rider Gavv via a mouth-like belt to stop Granute's attacks and save people.

After the events of the series, Shoma continues his research for "Light Treats" to replace Dark Treats, Hanto continues his research as a freelance writer as keep daily records of the battle of the Kamen Riders, and Rakia remains alone in the Granute World. However, a new incident occurs in the once peaceful human world, forcing Shoma to rush back to the battlefield. What serious abnormality has occured to Hanto's body? What is the current state of the president's daughter, Lizel Jaldak, who is stuck in the human world? The final battle of the candy Kamen Riders begin!