Kamen Rider Den-O (仮面ライダー電王, Kamen Raidā Den'ō?, Masked Rider Den-O) is the seventeenth installment in the popular Kamen Rider Series of tokusatsu programs. It is a joint collaboration between Ishimori Productions and Toei. It premiered January 28, 2007 on tv asahi, and concluded airing on January 20, 2008.

Along with the usual film adaptation that Heisei Kamen Rider series have released during the late summer of their broadcast run, Den-O had a second film released in the spring following its broadcast run which grossed 730 million yen and a series of 10 OVA shorts, both of which are firsts for any Kamen Rider. Continuing the trend, Kamen Rider Den-O also had a third film released in October 2008, the first for any Kamen Rider series and a second series of 10 OVA shorts set for release in November 2008. Takeru Satoh claims that the reason that Den-O has amassed such popularity is because of its comedic timing.

Source: Wikipedia