Three thousand years ago, the Vader Clan devastated Denji Star. Denjiland, an island from Denji Star, departed from the Denji Star and landed on Earth. In modern times, the Vader Clan was detected approaching Earth, the Denjiland computer awoke the Denjidog IC. It found five young people (who may or may not be descendants of the Denji people) to become the Denjimen in order to defend Earth, the Vader Clan's next target. The Denjimen began a long record of success with the defeat of Vader Monster number 00, Flying Squirreler.
As the battle escalated, they realize that they themselves are descendants of the Denji people. They were not alone because other descendants do exist, scattered around the Earth. Queen Hedrian, struggling in her attempts to make the world a living nightmare, the space wanderer Omnipotent Demon King offered his services. She accepted it, not realizing that the Omnipotent Demon King's true goal was the conquering the Earth for himself. He captured the Vader Castle, and tormented the Denjimen with his Omnipotent Monse. Hedrer goes into battle himself giant-sized, only to die a tragic death. The Denjimen find themselves helpless against Omnipotent Demon King and his monster until IC sacrifices himself to become a circuit for the DaiDenjin. Omnipotent Demon King and his monster are defeated. Queen Hedrian escaped to the North Pole, where she sleeps, encased in ice, waiting for the day to return.