This has got to be the shortest rider series which runs for only 31 episodes this year. Well, hope the new Kamen Rider Double (W) has a better story though it's intriguing for me (IMHO) to see the Ultimate Rider's War in Decade.
Kamen Rider Double (仮面ライダーW(ダブル) or Masked Rider Double W is the upcoming eleventh series in the Heisei period run of the Kamen Rider Series and the twentieth Rider series overall. It is set to premiere following the finale of Kamen Rider Decade on September 6, 2009
Plot Summary
In the ecologically-minded city of Fūto (風都, translated as "Wind Capital"), there are many windmills and the people live in harmony. However, the Sonozaki Family (園咲家) sell mysterious USB memory sticks called Gaia Memories to criminals who use them to become monsters called Dopants, committing crimes with the police force powerless to stop them. The hardboiled (or rather half-boiled) detective Shotaro Hidari works with the mysterious Phillip who possesses the true Gaia Memory. Using their own Gaia Memories, Shotaro and Phillip use the Double Driver belts to transform and combine into Kamen Rider Double to fight the Dopant menace.
Here's the promo video for the new Kamen Rider Double (W) after the trailer for Kamen Rider Decade final episode 31.