DaiDenzin is the ultimate secret weapon devised by the scientists of planet Denzi to combat against the invasion of the Vader Monster Umitsular when it begins to use its abilities, including the ability to become a giant, to destroy their world. Although they were able to complete the mecha, it was not in time to save their world; with the knowledge that another world would be right to possess the weapon in case the Vader came there, they sent DaiDenzin within the massive Denzi Land fortress to the planet Earth as their planet ultimately fell to the Vader Clan forces. When the Vader finally come to Earth, the activated Denziman were able to quickly use DaiDenzin's abilities to fight the forces.

The Denzi Fighter nose becomes DaiDenzin's back, the sides of the underside become the chest, and the lateral sides become the legs. Its main weapon is the Denjiken and it destroys monsters with its finishing attack, the Electronic Full-Moon Cut. Its other weapons are the Denzi Ball Meteor Hammer, the DaiDenzin, or Daidenjin Daidenzine Boomerang rocket punch. It also possesses the Denzi OO Return, where it uses the Denjiken to reflect any and all styles of attack back at a Vader Monster.