It was supposed to be simple. Sunset Shimmer had sent Twilight had to go to Amanogawa High to deal with some ancient enemies from Equestria's past, and Jack tagged along to talk some shop with Gentarou, and be backup if necessary. However, that was before he learned the Sirens were packing a set of Switches that made the Zodiarts look like cannon fodder. Luckily, Twilight had the brilliant idea to beat the Sirens at their own game during the Battle of the Bands the Sirens instigated, so Jack decided that a second band would be a good insurance policy. Only problem, he needs a band...

How about a bunch of other Displaced Kamen Riders?

Cross with Tales from a Displaced Wizard by shendari, A Golden Drive Through Equestria by Psyga315, and Harmony Damashi by ANDIE