Books in the Go, Go, Loser Ranger! series in order

"When the Monster Army invaded Earth thirteen years ago, the Divine Dragon Rangers rose up to stop them! With the war raging on, these great heroes are mankind's last hope! ...or are they? In truth, the invaders were subjugated within a year, forced to continue to crank out a monster a week for the Rangers to crush in front of their adoring fans! But one monster has had enough. Something has to change! He'll rebel against the might of the Dragon Rangers and destroy them all...from the inside!" --

"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 he 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...?"--