Baku and Nem become members of the Kaiju Countermeasure Agency. The giant robot, Code Zeroider is humanity's hope in the face of evil monsters! But the monsters are strong, and to save the pilots in dire straits, the Ultra Big Kamen Rider ZEZTZ descends!

The head of the police force's National Public Safety Commission, Chairman Shuma Kumon, transforms into Kamen Rider Mugen, and aims to transform the real world into a world of "daydreams". Standing in his way is Baku Yorozu/Kamen Rider ZEZTZ.

Step into the world of ZEZTZ with a special online event featuring a character show, talk show, and live performance!