The investigation into Ryuga's kidnapping leads to a man named Nabeshima. But to get the answers he needs, Ryuga must cross the border to Seito...

Now hidden in Hokuto, Sento and Ryuga try to learn more about Takumi Katsuragi from his mother, and find his hidden project data.

As the three Prime Ministers of Japan meet, Blood Stark leads an attack on the Touto Institute of Advanced Matter Physics.

With the majority of his Full Bottles now in Night Rogue's possession, Sento reveals his trump card - a way for Ryuga to use the Build Driver.

Gentoku reveals the truth behind Sento's missing memories, and the reality may tear his and Ryuga's friendship apart.

Hokuto invades Touto, looking to claim Pandora's Box for themselves. As civilian casualty numbers raise, Gentoku's government instigates Kamen Rider as their military weapon.

A new contender in the Rider Wars appears before Sento and Ryuga, somehow weilding his own Sclash Driver. Hokuto's own Rider, Grease, has arrived.

Another clash between the Touto and Hokuto Riders ends with Ryuga struggling from the Sclash Driver's effects. The Hokuto Crows are given a way to power up by Blood Stark, but there's a cost...

In order to counter Ryuga's rampage as Cross-Z Charge, Sento is forced to use the Hazard Trigger. What is the cost of using this forbidden item?

Touto and Hokuto's governments have ordered a winner-takes-all battle to decide who keeps Pandora's Box. It's Build vs Grease to decide the victor of the Rider War!

Kazumi is bummed that Evolt has stolen the bottles of his lost friends. Sento travels to his mother's house in Hokuto for answers about his father, but he and Kazumi end up face to face with a new Smash.