Even in real life, humans are slowly destroying the planet. However, in Parasyte Earth may have a chance due to alien invaders. These aliens are parasitic, sometimes symbiotic, creatures that attempted to take over human bodies when they first invaded. Most Parasites succeeded and took control over human brains. Others failed to take over humans but succeed in controlling other animals, although this is considered a failure by the Parasite population. These Parasites develop a need to eat others of the same species as their host. Thus Parasites in human hosts eat other humans. Another failure is when a Parasite fails in taking over a human’s brain and instead controls a different part of their body. This is the case of Shinichi Izumi who has a Parasite in his right hand.
Shinichi and the Parasite, Migi, live in a symbiotic relationship. Migi, perhaps because of his failure, does not need to eat humans. Instead, Migi relies on the nutrients from the food that Shinichi eats. Since Migi needs Shinichi to live he protects him from enemies, Parasite and otherwise. However, Shinichi is not content being the only one defended from the Parasite threat. Shinichi feels the need to protect other humans with the abilities granted to him from his Parasite partner. Now, as a superhero of sorts, Shinichi does his best to defend other humans while trying to hide his partner and new life from his friends and family.
Having a consciousness living in his arm takes a mental toll on Shinichi. He fears being in a relationship due to the violence of his life. Slowly, he becomes less human, and shows less emotions, as he adapts to the violence of the world. On the other hand, Migi becomes more human-like as he adapts and learns from the human world.
Besides having detailed and engaging plot and characters, Hitoshi Iwaaki, the mangaka of Parasyte, employs a very original art style. Simple, meaningful, and emotional illustrations define his technique. This style, also present his other works such as Historie and Tanabata no Kuni, has netted him recognition in the form of the Kodansha Manga Award for Parasyte and being a finalist in the 2005 Tezuka Osamu Cultural Prize Grand Prize for Historie.
Sources: Mangareader.net, Mangaupdates.com