Thirteen years ago, the Nefarious Monster Army invaded Earth, but humanity's great protectors, the Dragon Keepers, defeated them in a single year! Every Sunday since, the monsters have been forced to act out humiliating defeat after defeat in front of the unsuspecting public. Determined to change this, a single monster, D, infiltrated the Ranger Force. With the help of the mysterious Ranger, Yumeko Suzukiri, D managed to seize one of the divine artifacts--the only weapons capable of permanently killing the monsters' immortal bodies! However, D's subsequent encounter with the Dragon Keepers led to his unfortunate end, so who will stop them now...?