Go! Go! Loser Ranger!

Thirteen years ago, the Villainous Army of evil attempted to invade Earth, faced by the super sentai squadron known as the Dragon Keepers, and their super weapons, the Divine Tools. The evil army, however, was defeated within a year, all of its executives wiped out, and the surviving (and almost immortal) foot soldiers have been forced ever since to reenact their defeat to the Keepers in front of a crowd of spectators every Sunday. Tired of the charade, and realizing that this amounts to little more than slavery, one of the foot soldiers rebels, and decides he will defeat the Dragon Keepers by infiltrating the organization.