Is this rider Vlam gonna be someone with Saga vibes? He sides with neither humanity or the Granutes? As a double or triple agent?

I imagine his finisher will involve hanging his enemies.

Another indicator of this is the show's opening sequence. Early on, our two existing Riders appear alongside bubbles featuring their Rider forms. Sachika appears in this sequence alongside conspicuously empty bubbles I'm guessing will be filled with her Rider form in the near future.

That better be true!

Conspicuously empty bubble

Donburako!

Avataro!

This makes me wonder if the rumor about Vlam being the 3rd main Rider isn't 100% accurate.

Seeing as how he's been said to be a Granute government agent, maybe he hears about the red Gavv and his chocolate sidekick without a mouth-stomach, does an investigation on Earth, helps the heroes out for a bit, then leaves the plot to go do his own thing on the Granute homeworld (which would almost certainly be covered in a V-Cinema), while occasionally providing intel and/or extra assistance to the heroes at critical moments.

And then sometime after he's written out of the plot, Sachika gets her Rider powers and steps in as the "real" 3rd Rider of the trio. Or alternatively, he's the catalyst for Sachika getting her Rider powers and he gets killed off.

Hmmmmmmm

I love the pigtails!
Would feel on-point for a gyaru Rider in my opinion.
Also the bubbles are yellow implying a yellow color scheme like the design.
Maybe Vlam is like Demons in terms of being kind of outside the Secondary/Tertiary status.

While I do like the design a lot (I for one, never thought about dango being used, and I think breastplates like that would be hilarious to see), I'm nooooot inclined to think that this is a real leak. Haven't seen any of the more reliable leakers share anything about that design. Guess we'll just have to wait and see.