In the world is divided into seven Masters, each with the colors from red to violet to black, one is assigned a tattoo once they reach the age of eighteen. Polen is not your average boy in this world, with an older brother who received his tattoo far too early, no parents, two younger sisters, and brains that far exceed the norm. He is destined for greatness, but even so, no one was expecting him to gain the highest rank possible, Onyx.
Polen quickly realizes the tattoos, especially the one of Onyx, are not all that they're made out to be; so, due to his own personal experiences, he joins the rebel group aiming to end the practice of the inking. Along the way, as he matures and learns and grows, he encounters many people, some of them true friends, some of them traitors, and some of them simply allies or enemies.
Polen soon learns that rebelling against an age-old system isn't as pretty and easy as he thought as he fights family, watches friends die, enemies get destroyed and innocents killed. Though Polen never considered himself fighter, he has no choice - after all, it's all for the sake of humanity itself.
And besides... if he doesn't fight, he will die.