In the year 22XX, the drastic decline in the human population prompts the government to accept races from allied planets. Genetic mixing results in the birth of new species with special powers. On his 18th birthday, a young man named Yuuki discovers that his father belongs to the "hero" tribe, while his mother is from a tribe of plant-manipulating beings that were supposedly wiped out due to the planet's accelerated mechanization. Consequently, Yuuki possesses the powers of both tribes, but he questions which side he should aid with his abilities.