The story revolves around the nine previous universes of the Heisei Kamen Riders merging into one, something that would destroy all the worlds. To prevent this, Tsukasa Kadoya transforms into Kamen Rider Decade and is told that to protect his own world he must travel with Natsumi and her grandfather to the other Kamen Riders' Worlds called A.R. Worlds (Another Rider's World or Alternate Reality World) and eliminate the anomaly in thatworld. Along the way, confronting the mysterious Narutaki and the thief Daiki Kaito, they are joined by Yusuke Onodera of the World of Kuuga and Kivala of the World of Kiva.
Cast & Credits
What sets this KR apart from the others is the fact that it features loads of different Riders rather than just one. The way that Decade interacts with the other Riders and the problems in those Riders' worlds is great and makes for a lot of variety.
(This KR has 2 songs by Gackt so you know it must be good haha!)
The story starts off great and stays great throughout until the very end. I thought that the ending was good but at times it felt like the writers were running out of ideas.
Anyway, I would say that this KR is great for KR newbies. Since it has all the characters from Heisei, it gives you a taste of what the other Kamen Riders are like and you can see which other KR series you might be interested.
=NOTE= The actors playing the different characters (e.g. Kiva or Kuuga) may not be the same actors as in their original standalone series. Some of them are the same but a lot of them aren't so you'll still have to watch those original series to get a feel for the main cast and see if you really like it.
Anyway! Kamen Rider is very much targeted at children (we all knew that) but I (20 years old at the time) still thoroughly enjoyed it!