Modern society is completely peaceful, the few men typically having leading-type positions, and commonly being of gene types that grant enhanced decision-making skills, while the females are in charge of lesser positions. Men are assigned Registers - emotionless, drone-like women - whose purpose is to document all actions a man takes, as men's DNA contains elements of destructive desires that cannot be eliminated, while acting as his assistant. The story begins at the time when a 500 kilometer in diameter ring-shaped structure had appeared near the Earth five years prior. Dispatched from nearby Markanan space station, several female astronauts were about to investigate its nature when it produces a massive energy blast which destroys the space station and a large portion of the surface of the Earth, after which it disappears. This instigates the mobilization of a special group of men and women with specific genetic characteristics, who set out aboard the Bilkis spaceship to investigate the origins of the ring, and the possible connection with mysterious alien technology found in Jupiter's moon Ganymede. During their voyages they encounter several instances of the Ring technology, which they fight with the giant mecha, called 'Shaft'. The technology of Shaft is mysterious and the mecha requires very special skills to be piloted. Along the way, they also encounter situations and people which make them question their nature as 'superior', and raise doubts about how 'perfect' their society really is. Characters Mika Seido Mika is the main protagonist of the story. She is short but has considerable strength, though it is explained that she has the genetype white, leading to her being mocked by other characters as being inferior. Mika is much more passionate and aggressive than many of the people around her, but is also extremely loyal. Mika was very close to her "mother," the woman who genetically engineered her, and her sentient dog. Her friend Ryoko was killed in the previous year, and she blames Amagiwa for her death, believing that he murdered her to save his own life (although since in this society humans are considered to be nothing more than the sum of their genes, Ryoko's death would never be considered murder since she had an identical twin). She repeatedly threatens him because of this, but finds it bewildering that he is so confident in her potential and abilities, especially since she is a "white." Mika eventually teams up