AD 2199, the “degration” virus breaks out, hence biological gene becomes indefinite, species started merging, resulting in the birth of unexpected new living creatures; humans who has fused with other living creatures are called “hybrids”. The collapse of civilisation, the world plunges in chaos; some humans received inconceivable powers, others would rather die, and there are some who hunt for the rare gene, making a living out of finding solution for the cause of the hybrid incident – they are known as The Hunter G.