Other Title: 仮面ライダービルド-裏切りのデスマッチ, Kamen Raidā Birudo-Uragiri no Desumatchi
Summary: Sento went into Hazard form in order to try to protect the Pandora Box
from Rogue. However, he went berserk and lost the Pandora Box to Seito.
Not only that, but he also attacked Misora! It was just then that
Misora’s bangle started to shine again… One week later, Grease, Cross-Z,
and Build are summoned by Seito to participate in a 3 on 3
representative match. However, the identity of the spy who was involved
in the robbery of the Pandora Box is not yet known. As the
representative battle wages on, Nanba Heavy Industries’ chairman slowly
starts to smile…