It's been ten years since the Skywall Disaster, has happened. Unidentified monsters called Smashes are running loose, and the only one who can battle them is a rider with Bottles. Named Kamen Rider Build. Meet Kiryu Sento, as he and Ichika Banjou try to unravel the mystery of Pandora's Box and the organization known as Faust. Are You Ready! Henshin!

An archaeologist named Riku Hitsu, accidentally unleashes a violent species called Metoryu, sentient beings using the power of prehistoric creatures and common earth elements, during an archaeological dig. Using the power of the Kaseki driver and Dimagos, egg like devices. Hitsu becomes Kamen Rider Kaseki to combat these foes and to prevent humanity's extinction.

When the World is put into danger, the Riders and Cure always come to the rescue! But that's in their individual world. What happens when the world of Infinite Build, Accel-Aid's world, and the Pretty Cure worlds collide? Well a crossover that trumps the Taisens!(Which isn't a high bar) Will the Riders and Cure prevail? Or will they fall to Tri Kaiser?