Other Title: 仮面ライダービルド-西のファントム, Kamen Raidā Birudo-Nishi no Fantomu
Summary: There was never a clear winner from the result of the representative
battle! Seito uses this opportunity to make their move to overtake the
Hokuto government! Grease and his gang immediately head towards Hokuto
to check on their lands. Meanwhile, Ryuga is aching to fight them off,
but Sento stops him saying that it would be considered an act of
invasion. After their sudden invasion of Hokuto without warning, the
last of Hokuto’s military weapons are standing up to defend their
homeland…