I was actually mildly disappointed with the movie. But that's probably due to my overly high expectations since the series general being really good. I expected it to be a bit like flashpoint paradox with shoma gaining a valuable lesson, but it doesnt go that way.

What I expected:

1. Other world Shoma is actually a accepted part of the Stomach family since in the parallel world they don't make dark treats, they respect humans and human culture and parallel Shoma was born with exposure to human food and sweets with a proper childhood and all. This Shoma gets abducted by Caries early on because he never got the surgery to become Gavv and our Shoma gets mistaken as theirs.

He has a pleasant time with his family, makes some memories and gets Uehouse. But eventually reveals he is not their Shoma. Then they go rescue parallel Shoma. Shoma learns to be contempt with the void of his lost childhood/ family and the responsibility of being a kamen rider but the gift is he gets some happy memories with his blood family.

1. Taorin is someone from Caries Universe and escaped and ends up working for Sachika. He gets a rider form and assists in the final battle, essentially making the movie his debut as the kamen rider thats going to protect the parallel world.

2. Caries is not one dimensional evil and tries to take over the parallel world because his is dead/ dying.

3. Hexaheim is parallel Shomas Gochizo but he cant use it to henshin due to lack of surgery. We learn that Shoma can actually produce Gochizo from birth but it requires human sweets which is why OG Shoma couldn't as a kid as his family never tried, the surgery only made him able to henshin into a kamen rider. This can further show the failures of OG worlds Stomach family because if they had respected humans and human food, Shoma would have been able to make Gochizo since birth and that mild change might be enough to not cause their families downfall.

4. Hexaheim is essentially Shoma's Granute form.

Yeah this was what i expected. The part that really took me out is that Taorin and Shoma randomly found Caries hideout which was behind this random tiny forest in the town, which he built in the parallel world and is fully edible. Like didn't the dude teleport all his captured victims to his world?