Tiny creatures called "Parasytes" have arrived on Earth with the sole purpose of taking over human brains and preying on mankind. One latches on to ordinary high school student, Shinichi Izumi. Whilst he is able to fight it off before it reaches his brain, it is now stuck within his right hand. But a strange relationship develops between himself and the creature he calls "Migi," and before long they begin to encounter other Parasytes which launch savage attacks against them and endanger the lives of his friends and family. Shinichi and Migi have no choice but to work together and hurl themselves into the fight against an ever more complex and aggressive enemy.
It has become all-out war between humanity and the Parasytes - the tiny creatures who are rapidly taking over the brains of the human populace. But nothing is black and white in this struggle. Why have the Parasytes come to Earth? Are they here to cull our numbers? The planet needs to be preserved, but we also want to protect our loved ones. Amidst this conflict of values, Shinichi and Migi must continue to work together in the escalating fight against the Parasytes.