Young human is kidnapped by uknown organization that performed some procedure on him. Now he tries to adupt to the life in Equestria and discover the old mystery that is thousands years old by becoming a superhero named Kamen Rider Build.
18 years ago, a strange, celestial body crashed just on the outskirts of Canterlot. A mysterious box was found and studied in the Canterlot Research Facility. Despite the time and effort, its secrets have yet to be unearthed....until now.
Twilight Sparkle and Sunset Shimmer have a leisurely talk on the couch. It is the most important–and dangerous–event in the history of both their worlds.
Sento finds himself in Ponyville, where a mysterious villain named Faust steals his arsenal. He must now "build up" new forms by defeating new Smash. Are You Ready? (Kamen Rider Build crossover.)