Blood Stark's identity is revealed, and Sento races against time to finish a counter-measure against him.

Pandora's Tower is complete and Evolt stands ready to destroy Earth. Kazumi is still angry with Gentoku for killing his friend and challenges him to a fight; Sento works on a way to harness Pandora's Box into a power-up for Build.

Sento learns that his father actually is alive; Sawa goes to find the one Faust experiment that, to their knowledge, has no relation to the Kamen Riders; Misora discovers that the Best Matches are about her.