Aliens are taking possession of humans so they can fight their war. In Space, the Columbia shuttle is attacked by one of them and comes crashing to earth. Thus the story takes place depicting the struggle between these aliens and some militants.

(From Manga Updates)
After a nuclear war turns most of the Earth into desert wastelands, surviving humans had used the sands in order to survive. One of them is a professional mercenary named Sunabozu, who makes a living by hiring himself out to anyone who needs his talents.