In an alternate world, the Cold War has continued to persist for 140 years. As a result, the world was divided into two factions: the West Block, and the East Block. As the Cold War drags on, the tension between the two factions, as well as the amount of nuclear weapons they have, rise. Mylene Hoffman is a female cyborg who is a spy for the West Block. Together with three other agents, Mylene partakes in various missions issued by her superiors.
Eiichir? Maruo (nicknamed "Ei-chan" for his grades being straight "A") is an honor student, bookworm, and is not interested in anything other than studying. In order to solve his problem of lacking physical strength, he enrolled a tennis school and soon found the fascinating side of tennis. Being a tennis newbie lacking physical strength, he supplement his shortcomings with his excellent observing and analyzing skills.
In Tokyo, an impenetrable field known as "Hell's Gate" appeared ten years ago. At the same time, psychics who wield paranormal powers at the cost of their conscience also emerged. Hei is one of the most powerful of these psychic agents, and along with his blind associate, Yin, works for one of the many rival agencies vying to unlock the mysteries of Hell's Gate.
Kenshi Masaki is the half brother of Tenchi Masaki and used to live in Japan, that is until he was summoned to the land of Geminar. The Land of Geminar has been witness to an endless amount of wars that have been fought using Seikijin, bio-mechanical weapons controlled by a capable warrior called a Seikishi using magic power called Ahou. It is revealed that Kenshi is an amazing Seikishi and it seems someone has a reason for Kenshi to be in Geminar, but who and why are not known.