|Humans born with mysterious powers known as Gosei Angels moved to the Gosei World around Ten Thousand years ago. Using the Heaven's Tower as a bridge between the dimensions, the Gosei Angels made it their mission to protect Earth. When the Heaven's Tower (which is a passage between Gosei World and the Earth) is destroyed by the evil Warstar, only five Gosei Angels are left on the Earth to complete this mission. The Goseigers are assisted by the grade school student Nozomu Amachi, his oblivious father Professor Shuichirou Amachi, and the robot Datas, in which their leader Master Head uses to communicates with.
The Goseiger are able to defeat the remnants of the Warstar and the Yuumajuu are released from their imprisonment are become their newest enemy. Buredoran, who the Goseiger thought was part of the Warstar was actually undercover and is actually from the Yuumajuu. Ten-thousand years ago, Groundion Headder battled the Yuumajuu until he got separated from his Gosei Angel allies. Ending up in a glacier, Groundion made a pact with the planet itself to take the form of Gosei Knight and cleanse the Earth of any threat. Gosei Knight is at odds with the Goseigers because he doesn't care for human life.