After Kamen Rider Gaim introduces himself to Kamen Riders Wizard and Beast, he is able to return to his world before Amadum appears. He then overpowers the summoned Kamen Riders as he tells Haruto and Nito that the children will fully transform into monsters soon. Before Amadum and his monsters attack them, Nito gives Haruto two of his rings, so he can escape with the children, and he also steals the Fourze Kamen Rider Ring. Amadum summons Kamen Rider Decade to retrieve the stolen ring. After they escape, the children tell Haruto the reason why they want to leave their world and they want him to kill them if they transform into monsters. While Haruto wonders what can he do to save the alternate Koyomi, Kamen Rider Decade appears, cancelling his transformation. Tsukasa Kadoya wonders why Haruto has entered the World of Monsters, to which he replies that he heard voices that needed help. Nito sneaks into Amadum's lair, however he knows that Kamen Rider Beast is in his lair, so he summons all of the Kamen Riders and tells Nito that the Kamen Riders' power are born in the World of Monsters, including Kamen Riders Wizard and Beast and he wants to gain the powers for himself. Nito transforms, but he is easily defeated by Amadum's monster lackeys and he starts to disappear into dust. While Rinko and Shunpei are taking care of the children, monsters appear to attack them as Tsukasa threatens Haruto to return the Kamen Rider Ring to Amadum. Tsukasa arrives at Amadum's lair, along with the boy, and returns the ring to Amadum. Amadum tells Tsukasa that he is imprisoned in the World of Monsters and he wanted to escape out of this world. Haruto also appears, so Amadum summons all of the Kamen Riders to attack Haruto, but they refuses his order. Tsukasa tells Amadum that Kamen Riders fight for freedom, besides justice. Amadum then summons other monsters to attack the Kamen Riders, so Tsukasa and Haruto transform. After defeating the monsters, Amadum forces the boy to pray for help. The Kamen Riders tries to stop him, but Amadum reveals his true monstrous form and manages to absorb all of the Kamen Riders' powers. The boy decides to stay in World of Monsters after hearing Haruto's words on what it means to fight for, as he prays to call someone. Kamen Rider Gaim arrives as he overpowers Amadum, while also learning the meaning of being a Kamen Rider. The Kamen Riders regain their powers as they change into their most powerful forms to defeat Amadum. After Amadum is defeated, the Kamen Rider Rings vanish as the Kamen Riders return back to their worlds. Tsukasa continues his journey as Haruto tells the boy that he does not need to become a monster, but can instead become a Kamen Rider, giving the boy the Infinity Ring before resuming his journey in his own world. As Wajima, Rinko, and Shunpei bring Koyomi, who has recovered, to see the boy, she says his name: Haruto.
This episode contains examples of the following tropes:
- Crossover: Like the last episode before it, every single Heisei Kamen Rider is assembled, including Kamen Rider Gaim.
- Early-Bird Cameo: The second appearance of Gaim.
- Fake Shemp: As in the previous episode every previous Rider other than Decade (who appears out of suit for a proper appearance from Masahiro Inoue this time instead of just a VO) and Den-O (who has Momotaro's usual VA) are played an assortment of voice actors and never shown out of suit.
- Uncertain Doom: Beast gets taken down by Amadum's minions and fades away and that's the last seen of him in the show proper. Given he came from a point in time before the show's final battle however he was likely just sent back to then, and The Fateful Sengoku Movie Battle would indeed show him alive and well.
