A dying Ai requests Yusuke to overcome his angst and fight to protect everyone's smiles, and so Kuuga and Decade work together to destroy the remaining Gurongi.
After meeting a mysterious man who is disgusted with the human/Fangire treaty, Tsukasa later encounters Kiva-la, who uses her power to send him into another world where he is attacked by Kamen Rider Kaixa.
Back in the World of Kiva, after having fed on many humans, the Beetle Fangire arrives at Castle Doran with the intent to kill Wataru and take his place as the King.
After being caught up on current events, Tsukasa makes his way to Castle Doran to save Yusuke as the Beetle Fangire absorbs the Arms Monsters into himself.
He takes back the Kiva power and helps Decade battle the Beetle Fangire, mortally wounding him with a Darkness Moon Break/Dimension Kick combo.
Their fight is also interrupted by Decade, having just defeated Impaler and now turning his sights on Knight, easily overwhelming him in Kiva's various forms with Shinji watching.
[7] Arriving in the World of Blade, Tsukasa assumes the disguise of the Chief Waiter of the BOARD Corporation, an organization whose agents become Kamen Riders to battle the Undead.
[10] After Tsukasa recovers the Faiz Gear, he learns Diend's reasons for wanting the belt before Takumi regains it so he and a shocked Yuri can escape on the Autovajin.
While this occurs, the remaining Lucky Clover members start taking over the school to sire more of their kind until Takumi arrives to fight them in Orphnoch form.
After easily overcoming M-Yusuke and treating him to pudding for answers, Tsukasa learns that the Imagin lost his physical form some time before they arrived.
When Tsukasa forces the three out and they enter Natsumi to fight him, Decade uses Agito's power on each form while a mysterious Kamen Rider-like figure and his lackies attack a group of delivery men, with the Alligator Imagin taking advantage of the chaos.
After Decade saves Den-O's life and attempt, Diend makes his presence known with his Riotroopers holding the Alligator Imagin at bay as he once more offers Momotaros a physical form as a DenLiner.
As Momotaros returns to the DenLiner, only to receive a violent welcome back from the gang, Tsukasa and company were about to enter the World of Kabuto when they get an unexpected visit from the Imagin Sieg.
Tsukasa talks with Mayu more about her brother after attempting to help at her grandmother's oden shop, the Heaven House, and when walking back to the Hikari Studio they are attacked by a Geophilid Worm.
Like Tsukasa, Daiki learns of the three scrolls of the Oni classes, and he convinces Asumu to become Hibiki's pupil again, before taking his leave to Zanki's dojo where he offers a proposition.
The next day, after suffering a Narutaki-induced vision of the future resulting from their actions, Natsumi finds Daiki, who uses Asumu as his cover to steal the final scroll.
As Natsumi goes out to see her TG Club friends and teacher for a high school reunion, Tsukasa and Yusuke have a short encounter with Narutaki who congratulates him on getting his own world.
As Tsukasa and company meet the head of area management committee, Junichi Kaito, Larc and Lance battle the Darkroaches until they receive aid from Diend.
After escaping the angry mob, parting from Haruka and Shin, Kaito and Tsukasa find Natsumi who tells them that Yusuke has been kidnapped by the Roaches before Junichi arrives.
After remembering the events leading to his brother's enslavement, Kaito is reluctant to fight as he and Tsukasa transform to follow Junichi, leaving the brain-washed Yusuke behind and taking Natsumi to undergo the process as well.
Transformed into a monstrous version of Kamen Rider Diend, Chinomanako summons a mass of Nanashi to attack the mortal realm to Narutaki's horror of the newly born abomination.
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.
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.
World, finding himself in a baseball uniform, Tsukasa notices the people are acting strange while saluting each other before he, Natsumi and Yusuke are singled out as rebels against Dai-Shocker with Propheta Cruentis, Go-Jaraji-Da, and Camponotus Worm Maxilla appearing to exterminate them.
Evading the military police, Tsukasa and company find Masahiko being attacked by Dai-Shocker Soldiers as Amazon and Yusuke come to his aid.
Getting Amazon's trust, in spite of Tsukasa's feelings about the boy's sudden change of heart, Masahiko is brought to the Hikari Studio as he contacts Dai-Shocker to their location, with the Ten-Faced Demon Llumu Qhimil appearing with Apollo Geist and monsters.
While Decade battles Apollo Geist, Kuuga and Amazon deal with the monsters until Llumu Qhimil joins the fray, overpowering the riders single-handedly.
After being saved and telling his sister that Dai-Shocker are not the good guys, and learning that Amazon's leaving because of him, Masahiko runs off to get the GiGi Armlet as Decade battles Llumu Qhimil.
Meanwhile, Super Apollo Geist resurrects the Beetle Fangire, Paradoxa Undead, Tiger Orphnoch, Taurus Ballista, Alligator Imagin, and the Phylloxera Worm.
After promising the world to Daiki if he dies, Tsukasa arrives to stop Guy as he is about to consume Natsumi's life energy, fighting both Super Apollo Geist and the monsters with aid from Kuuga and Diend.