The last thing Sento and Ryuga remember was a shadow that was right outside Nascita, which they deduce to be the culprit in this mysterious phenomenon. Regaining their composure, Build and Cross-Z are confused as to what was going on and notices both Sougo and Geiz and calls them by their civilian names. Zi-O and Geiz manage to win, however, it results in a black haze coming out of Build and Cross-Z, which seeps deep underground.
That night, Sougo and Geiz re-encounter Sento and Ryuga, however, Geiz notices that the two Riders weren't referring to anyone any their civilian names, but their Rider names, raising his suspicions. The two fight Cross-Z and defeat him, who then revealed that both Build and he are from a different time, and vow to come back with him to defeat Zi-O and Geiz, before running off. The two continue to investigate the area, before being ambushed by Ryuga Banjo. With the three transformed, the two defeat Build, who claims he is the real deal as he escapes into thin air. However, they encounter a supposedly evil Sento Kiryu who attacks them.
A mysterious ring of 270 diameters appeared in the sky, and both Sougo Tokiwa and Geiz Myoukouin head to investigate.
