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In the far distant future, hideous monsters roam the Earth, threatening the lives of all people. Genma, the evil ruler of the Mah tribe, has become obsessed with fathering an Heir. Convinced that a child born of a Hito woman will have amazing powers, he sets his sights on a young Hito woman. In exchange for her village's safety, Non agree to bear Genma's child. She gives birth to twins and names them Loof and Jin. Jin is left for Non to raise among the Hito, as Loof is taken to Genma, and raised to be the prince of the Mah tribe. Although Loof and Jin live in two separate worlds, their fates soon become intertwined as Loof is banished from Mah tribe once he appears to possess more human than wizard physical characteristics.
The story is set in the near future not long from now, when humanity has completed an orbital elevator and begun developing the outer planets in earnest. An enigmatic extraterrestrial enemy known as "Obliquus" has set its sights on the solar system, and humanity enters a state of war with the first aliens it has encountered. To counter the enemy's overwhelming technological superiority, the Khronos Foundation has assembled the descendants of every country's heroes from Japan's Musashi Miyamoto and Ryōma Sakamoto to France's Napoleon and Joan of Arc. The foundation then fuses the descendants with "Gear" battle suits as special biological weapons, thus giving birth to "Khronos Gear."
Japan builds a large space power plant called Saint Elmo in the planet Mercury. The plant supports Earth with its large solar energy supply, but, when there is an abnormality at the plant, Earth has to send several technicians to fix the problem.