A Rider's Challenge Kamen Rider: Dragon Knight : Season 1 Episode 4

While talking with Len, Kit discovers that the Kamen Riders were the defenders of the mirror world of Ventara. The mysterious Advent Decks were actually stolen from the Riders and given to certain people on Earth. Then, Len challenges Richie to a battle and ends up sending him to the Advent Void, where he will be trapped forever. Realizing how dangerous these battles are, Kit quits being a Kamen Rider.