Saiga Junki enjoys his school life as a normal high school student. One day, he hears that his father, an archaeologist missing for the past 10 years, was found dead in ruins located at Iwate Prefecture’s Mt. Kurokami; thus, Junki travels there.
Junki blacks out while in the ruins and witnesses a strange vision. Upon waking, he finds a gold bracelet left beside him with an inscription that reads, "The Great Reideen..."
At the same time, a meteor falls from the sky and a large mechanical beast appears out of a lake.
What is this gold shining object that appeared from out of Mt. Kurokami as if in response to the mechanical beast?
The story illustrates Junki's transference between his normal life during the day and his strange life of fighting by night, the embarrassment of peers, conflict, and human drama in detail.
Will the great power that Junki happened to obtain bring him glory... or fear?
*This is a remake of the 1975 series Yusha Reideen.