The Underground Empire Badan makes its move, intending to invert the world. Kouta and Mai are pulled through one of these inversions where the discover a boy named Shu, who also holds the power to invert the world. As the Riders fight to protect Shu, Fifteen appears again, seeking Shu. As Kouta flees, past Riders gather and fight one another, split between the Showa and Heisei era Riders. But, the truth of Badan is not as it seems…

Heisei Rider vs. Showa Rider: Kamen Rider Wars feat. Super Sentai

While in the middle of fighting, the Gekirangers and Mere are teleported to Hong Kong, along with Rio and various other martial artists around the world. Just as Rio and Jyan were about to fight, they meet the mysterious Lao Fan before seeing others brought to the island as well.

Juken Sentai Gekiranger: Nei-Nei! Hou-Hou! Hong Kong Decisive Battle

When Earth is tearing itself apart by means of crime, pollution and war, aliens choose the time to invade, taking advantage of the lowering of everyone's guard. The Japanese government establishes an elite police organization known as Blue SWAT to combat the aliens, known as the Space Mafia. The aliens attack by possessing humans to obtain their goals. When an alien possesses the chief of the Blue SWAT unit to infiltrate the organization, it manages to completely demolish their building of operations and murder all but three SWAT members; Shou, Sara and Sig.