In the not so distant future, deep down under the ocean floor, humanity discovers a strange, anomalous substance. Once collected and brought inside the search vessel, the crew of the submarine (barring the captain) attempted to examine it further. However, when the container was unsealed, the substance instantly turned invisible and blended into the air. Ten minutes later, the captain walked into the room, worried about his crew, only to find them in a state of absolute madness. One was rolling on the floor sobbing, another was screaming loudly while covering his ears. Sitting amongst them and many other wailing men was a woman, the captain's daughter and a crewmate in training, who simply stared at him, with a huge smile on her face.

Liao. That's what we called it then, that's what we call it now. The etymology of this name is unknown, as is the person who named it. An extremely unusual substance, it is usually extremely toxic to humans, though once purified using a special machine it's capable of shifting itself into anything you desire at the cost of your life force. From a cup of water to a gigantic gattling gun. For unknown reasons, its negative effects are significantly reduced on female test subjects, with the purified version being especially harmless to young women.

Skipping a couple of centuries forwards, we arrive at the present time. The age of Sirius, our glorious Empire. Once the Liao had been "tamed" by humanity, it greatly helped our ascension into the space age. Leaving that decayed blue rock behind, we've spread far and wide across the galaxy, facing no competition along the way... Apart from our own kind, of course. Humans are that kind of animal y'know? When prosperity is at our doorstep, we immediately start fighting each other for the biggest slice of the pie.
Liao-powered tanks, spaceships and mechs were used at first in planet-wide wars for the control of entire solar systems, but there was one major problem. Although they were extremely powerful, they were also extremely costly, and not just in terms of money. Since machines do not have life force, it was common for soldiers to use animals, plants or even captured prisoners (extremely illegal, by the way!) as fuel to power their weapons, but even then they would barely last half a day before shutting down. Liao weapons are convenient for small scale conflict, but bigger and bigger weapons require more and more life force, rendering the substance itself borderline useless for large scale space battles.
That was, until a group of scientists from the glorious Sirius Empire had made a major breakthrough! Researching further into the connection between females and the substance, it was discovered that, using special devices strapped around their heads, girls from 9 to 20 years of age could tap into the Liao at a very minimal cost, one that could be easily satiated with a special carbohydrate, lipid and glucose diet. The young women of our nation had been given a blessing.