Geiz was able to return home from Helheim successfully, only now he has a renewed determination to kill Sougo at any time, and anywhere! Another Rider suddenly appears in the city, to be striking people down and taking their souls away! Takeru Tenkuji and Narita of the Mysterious Phenomenon Institute set out to capture this Another Rider, but as soon as they reach the location, they see none other than... Kamen Rider Agito?!

Why does Sougo want to become a king in the first place? Sougo starts to tell Tsukuyomi about the continuous dreams he's been having. Just then, a giant event, just like the one in Sougo's dream, suddenly starts to manifest! A giant mecha suddenly appears in the sky! The demonic king's servant from the future, Kasshine suddenly appears! And thanks to Decade's intervention during their fight, Sougo gets blown 50 years into the future...!