Tsukasa finds himself wearing strange clothes with another strange card as he, Natsumi, and Yusuke find themselves attacked by the Strange Demon Robot Schwarian and his Chaps as Kamen Rider Black RX battles them, with both sides believing Tsukasa to be Joe the Haze. When the Seamoon Fangire and Scorpion Imagin suddenly appear, Tsukasa becomes Decade to help RX out against the monsters with Agito's power as Schwarian runs off. After Natsumi stops RX from attacking Decade, RX takes her words to heart and sees Tsukasa as an ally. From there, he introduces himself as Kotaro Minami and says that has been fighting the Crisis Empire. Everyone is confused at the sudden appearance of Imagin and Fangires in this A.R. World with Tsukasa reluctant to fight, once more. While Tsukasa takes pictures, after Natsumi offers him to embrace her world as his home, they confront a man named Guy who is behind the attacks. Introducing himself as Dai-Shocker's Apollo Geist, he knocks the Decadriver out of Tsukasa's hand as Natsumi takes an attack meant for him as the villain and his attendants leave. Natsumi is hospitalized beyond medical aid and Tsukasa is upset by Narutaki telling him that he is a danger to himself and those around him. Daiki visits Tsukasa and Natsumi, telling Tsukasa about Apollo Geist being from the World of X-Rider and possessing the Perfecter, which is the key to returning Natsumi to normal. Tsukasa goes off to confront Apollo Geist on his own, not wanting anyone else to get hurt, finding Schwarian as Apollo Geist attacks him for refusing to deleiver his offer to Grand Lord Crisis to join Dai-Shocker. With RX's support, Decade battles Apollo Geist before Diend interferes with his own Riders to steal the Perfecter. When Apollo Geist summons the Rhino Mutant, he convinces Schwarian to accept his offer of joining his group as Decade assumes Complete Form to use Kabuto Hyper Form's power to take out the summoned Riders. Apollo Geist escapes into another dimension with De