[TheRaizin]

We're going to need LOTS of shurikens!

Shinobi will start a year after the original series, with him having a new belt and suit that's just a refined and less kitbash-y version of the original suit. Basically, just make the stickers on the suit more pronounced.

The collectable gimmick this time are shurikens that correspond to a certain element and a sub-category skill/ninjutsu/ninpo. The element corresponds to a certain rider and the ninpo to what the rider can do. These shurikens are interchangeable with each rider, though, except one as their own Shuriken that is basically their rider form. So, basically, Hattari can make use of, say, Shinobi's "smoke bomb" shuriken while Shinobi can make use of Hattari's "Chain Lightning" shuriken. There's no form-changing per se, only changing the scarves on the riders. Think of Warframe's Syndanas.

Shinobi is Shadow
Hattari is Lightning.

Shinobi will make use of a horse as his transportation while Hattari will be using the bike. No mechs. I mean, we already have 'em.

There will only be three main Kamen Rider protagonists, the third one being the Q2 rider. Everyone else will be a pseudo rider like Night Rogue or Blood Stalk. This will be like Ryuki in that the true Kamen Riders have bug eyes while the pseudo riders have none. The pseudo riders are all the same guys that frog scroll dude summoned. 3/5 pretty much use the same base transformation item, but the toy has multiple ports to accommodate attachments that correspond to each pseudo rider's weapons. The remaining two being the captains.

Shinobi (the series, not rider)'s main upgrades would basically be consisting of traditional japanese ranks. One of his forms being a Shogun. Basically, forms are dictated by a rank, much like Ex-Aid's LVLs. Some enemies may have their base form in a higher rank than Shinobi or Hattari already. Each upgrade also gives the rider more armor. Duh.

Q2 rider that joins Shinobi is a kunoichi. She transforms using her sword in which she inserts her shuriken into the hilt. Much like Shurikenger. She only has two forms, her base and final. Kunoichi is Shinobi's sister.

And then for good measure the "Saber x Shinobi Movie Rider" is Okita Sōji, revived from the dead and brainwashed by the bad guys and transforms into Kamen Rider Kiku. With Touma having to teach Rentaro what he knows about Okita and together beat him.

The ending will have Rentaro defeat the main bad guy as usual, but train and lend his belt to someone else and go into hiding. Coming back into his solo movie with the movie form being a pseudo-rider version of Shinobi. Why does Rentaro leave? Idk, adult circumstances or something.

Opening theme will be a redux of IZANAGI and then an ending theme by LiSA or Sawano Hiroyuki.