Ryuunosuke Natsume is the son of genius inventor Kyusaku Natsume and overbearing Akiko Natsume, CEO of Mishima Heavy Industries. Using funds from his wife's company and the brain from his son's beloved cat, Kyusaku creates a revolutionary android called Atsuko "Nuku Nuku" Natsume. To Kyusaku's disgust, Akiko wants to use her husband's technology to create weaponized robots for her company's customers, resulting in Ryuunosuke getting caught within the explosive fights between his parents The android Nuku Nuku tries to live as a normal high school student, adopting the role of Ryuunosuke's elder sister, but usually ends up acting as her family's protector. Nuku Nuku will do anything to protect the ones she loves.

Meifon (and Taffei) talk about the space ships and equipment the Angel Links organization uses to carry out its mission.

In the mid-21st century, mankind has begun the exploration of space, and one company, Planet Catcher Corporation, has pioneered capturing asteroids and comets to mine the resources within them for use on Earth. On one such asteroid, Tortatis, lives 12-year-old Nanbu Ushiwaka - the only child ever to be born in space and survive. But survival itself is no longer guaranteed - a military satellite triggers a disaster during a operation to capture Halley`s Comet, and Ushiwaka and his fellow colonists must find a way to survive when both their country and their company abandon them. Can they escape before the nuclear reactor on the asteroid melts down? Or are they doomed to die as they lived, among the stars?

Fleeing from his own race, Orgun—an alien being with superhuman abilities and unearthly weapons—travels to Earth to find an answer to his origin. There, he bonds with a young man named Tomoru to defend Earth against the Evoluders, who seek nothing but destruction of other civilizations.