Other Title: 仮面ライダービルド-禁断のアイテム, Kamen Raidā Birudo-Kindan no Aitemu
Summary: The Sclash Driver has inevitably become a weapon of war, as the battle
between Cross-Z and Grease continues to escalate. Regardless of their
combined efforts, Build and Cross-Z can't seem to overcome Grease's
superior strength. Hokuto continues their march into Touto territory to
secure the Pandora Box and the nation's Fullbottles! Can Sento and Ryuga
find the means to defeat Grease? The answer may lay within Project
Build as Sento discovers clues and hidden information regarding the
existence of a forbidden item created by Katsuragi...