Arriving in the last world, the World of Hibiki, Tsukasa and company begin the search for Kamen Rider Hibiki when they are ambushed by the Makamou Kappa. An Oni in training named Asumu battles the monster until Decade uses Kabuto's powers to destroy it. On learning he is Hibiki's pupil, Tsukasa has Asumu bring him to his mentor. Upon seeing Tsukasa, Hibiki, who is shirking off from his duties as an Oni, believes him to be the legendary Ongekidō Grand Master. Meanwhile, Zanki slays a band of Bakeneko as Ibuki arrives to take them out as well. But when the last Bakeneko escapes them, Decade destroys it with the two groups as witness. Tsukasa visits Ibuki's school afterwards and talks with Ibuki and Akira about three special scrolls. Meanwhile, after failing to rob Hibiki as he takes his leave, Daiki is forced into becoming Asumu's mentor.

Using Ryuki's powers, Decade battles Gyuki while Ibuki and Zanki argue whose fault this was. When Akira and Todoroki join the fray in their Oni forms to save Asumu as he tries to protect them, with Decade joining them by using Den-O's Ax Form, they manage to defeat Gyuki. He runs off before regressing to Hibiki, and Yusuke and Natsumi find him shortly after. Later that night, after talking to Asumu, Akira and Todoroki confront their mentors to put aside their differences, with Tsukasa supporting them. Ibuki and Zanki promote them to the role of new teachers of their respective schools. Meanwhile, Hibiki reveals the nature of Gyuki to Yusuke and Natsumi as Daiki arrives to claim the last scroll.

When Natsumi realizes that this is the world from her nightmares, she becomes wary for Tsukasa's well-being. Finding him in a tuxedo and feeling that this is the final chapter to their journey, they witness Wataru and Kazuma leading their respective Rider/monster groups against each other. After Rising Ixa and Leangle are killed off in the fight, Tsukasa makes his way to Wataru as he grieves over Ixa's death. Meeting the Fangire Queen Yuki, they learn from Wataru that the Riders are fighting each other to maintain the existence of their worlds.

After fighting off the Riders, Super Apollo Geist takes Natsumi to be his new bride as he flees. Kazuma Kenzaki appears, saying that Tsukasa's existence is the real cause of the worlds blending before confronting him as Kamen Rider Blade in King Form in order to force him to leave the world at once with Asumu keeping Yusuke and Wataru from interfering as Decade is easily defeated.