Kamen Rider Decade is a Japanese tokusatsu television series and the 10th entry in the long-running Kamen Rider franchise. It follows Tsukasa Kadoya, a mysterious traveler who journeys through alternate worlds connected to previous Kamen Rider series. As he explores these parallel dimensions, he becomes involved in conflicts that threaten to merge or destroy them. The series is known for its crossover nature, anniversary themes, and appearances by legacy Riders.