Kamen Rider Yugou

Kamen Rider Yugou (仮面ライダーフュージョン, Kamen Raidā Yugou "Masked Rider Fusion) is a special crossover animated series between Kamen Rider and Senki Zesshou Symphogear. Despite being an animated entry, as well as a crossover, it is referred to as being apart of the Kamen Rider series. It also the first work of Kura Akuma. The series is meant to be a callback to both the Heisei and Showa Era's, borrowing from Ultraman Geed in certain aspects.

The tagline of the series is, "Here We Go! (さあ! Sā!)"

Plot
Many years, following Build and Ex-Aid's battle, Dark Decade invaded the Rider Worlds. The power he had gained in his exile had grown too great to handle. In the end, the world was destroyed. In one last ditch attempt to save Earth, Kamen Riders Ichigou, Decade and Build use their powers to merge the other Rider worlds together with their own, using themselves as the new world's core. As a result, Dark Decade's plot to destroy the world was foiled, and he and his forces have gone into hiding. However, as a result of the merge, mysterious organisms known as "Noise" have begun to emerge. The Riders themselves are nowhere to be found, leaving only those blessed by the power of the relics to protect humanity.

But...hope is not lost. During the war against Dark Decade, Build creates tubes containing the powers of all the known Kamen Riders. In the wake of the Merging, however, these tubes were lost, along with the FuseDriver, which allows one to mix together the power of two Kamen Riders together.

In the present day, a young teen named Hikage Sendou attends the Zwei Wing Concert, two weeks after the death of his father. In the middle of the concert, Noise suddenly appear. As he lies helpless, time suddenly stops as a man approaches Higake, asking him if he is ready to brace whatever the future holds. He holds a strange belt and four tubes out to him. Higake, spurred to survive, takes the belt and tubes. After twenty years of silence, the FuseDriver activates and creates a new hero: Kamen Rider Yugou!

However, there lies a terrible secret. One that Hikage is not aware of. He is the son of Kamen Rider...

...Dark Decade.