Sentai Daishikkaku

Thirteen years ago, the Monster Army attacked Earth, prompting the Divine Dragon Rangers to rise as defenders. As the conflict continued, the Rangers were celebrated as humanity's final hope. However, the war actually ended within a year, with the defeated invaders coerced into producing one monster weekly for the Rangers to battle in front of their supporters. A monster, frustrated with this arrangement, decides to resist. Seeking change, it plans to undermine the Dragon Rangers and eliminate them from within.