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.

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!

Seito delivers an ultimatum to Kazumi - fight for them as their Kamen Rider or witness the death of his family. A mysterious new adversary makes his way to Touto to confront Sento and Ryuga.

Kamen Rider Rogue has revealed himself; Misora collapses inside the base.

Misora sends Kamen Rider Rogue flying through Skywall; Souichi reveals to Sento that there is a spy in the Touto government.

Seito challenges Touto to a best-of-three battle to decide who keeps Pandora's Box; Sento works to find a counter to Black Hazard's berserk state.

Ryuuga is tricked into losing his match; Build and Rogue face off as Sawa arrives with the schematics stolen from Sento.

Kamen Rider Rogue receives the data on Build's Rabbit Rabbit form, forcing Sento to unleash Tank Tank form; Sawa's backstory is revealed while Kazumi rescues civilians; Nanba decides to not play fair, taking control of Seito and declaring war.

Despite their promises, Seito continues their assault against Touto. All this is made worse as Blood Stark completes a panel of Pandora's Box, and the Skywall begins to shift...

Blood Stark wonders how the Queen of Mars is still alive. Mysteries begin to arise as she singles Ryuuga out to become hope.

Sento suspects that since Evolt has the Lost Bottles, he also has his father; Evolt plans to reunite Japan while Gentoku mopes over his dead father.