A dying girl wakes up in a world where the only way back to life is winning mecha fights, except her mecha is possessed by something that might be more dangerous than death itself. Zhang San isn't a tool or a power-up; he's a separate will locked in the same body, and neither of them can win without trusting the other. The show builds its entire tension around two beings who have every reason to betray each other, forced to move in sync or die trying.

Gravely ill, A Gan falls into a world called Kong at the moment she is dying. In Kong, people pilot mechas and fight in the ring of fate, and whoever wins may earn a chance to live again. By chance, A Gan ends up partnered with Zhang San, an evil mecha that has a soul of its own, and her adventure in Kong begins. The twelve-episode ONA combines action, drama and science fiction around its mecha battles.