In the distant future, Earth's overpopulation drives humanity to seek out and colonize other planets. During one such voyage, the colony ship 'Mesopotamia' suffers a catastrophic malfunction, killing all but six of its passengers. These lone survivors manage to flee to a nearby planet, 'Terra II', which closely resembles Earth in many ways. However, each of the six is male, so in order to ensure their mission is not in vain, they establish six nations and continue their population through cloning and genetic engineering. Despite this, women still do not exist, and to compensate for their absence, they build highly advanced female androids — lifelike machines called 'Marionettes' — to carry out everyday chores and tasks. Yet these androids remain purely emotionless machines. One day, however, an ordinary young man named Otaru happens upon and also awakens three special battle-type Marionettes, who bear true feelings thanks to the 'Maiden Circuit' built inside them. From that moment on, it's his way to teach them about the world and help those emotions grow. And when a neighboring country makes a move for global domination, it falls to Otaru and those 'human' Marionettes he cares for to defend their nation.
