Parasyte -the maxim-

On a quiet night, unsuspecting high school student Shinichi Izumi is attacked by an alien creature that burrows deep into his right arm. The next morning, Shinichi comes to learn that this being, known as a Parasyte, is now a part of him.

As Shinichi and his parasyte continue their unasked-for coexistence, the parasyte in his right (migi) arm decides to take on the name of "Migi." Shinichi realizes that parasytes are involved in the ongoing mincemeat murders. Feeling alone in his discovery, Shinichi grapples with frustration. Unbeknownst to him, he is about to meet another parasyte for the first time...

As the number of mincemeat murder victims grows, Shinichi, alone in his knowledge of the truth, is in turmoil. When Migi suddenly alerts him to the presence of another parasyte, he is aghast to find that it is in his own school. Paranoid, Shinichi attends a schoolwide assembly, where the staff introduce a beautiful new teacher...

After the events involving Ryoko, Shinichi and Migi are slowly adapting to one another. But the closer Shinichi grows to Migi, the further he drifts from his family as he struggles to keep them from discovering his secret.

Running late to school, Shinichi sees Nagai in trouble with some punks. When Shinichi steps in to help, he meets a high school student, Kimishima Kana. Shinichi and Satomi share a close moment when she tends to his injuries, but his life is about to take a sudden turn with a single phone call from his father...

Struck through the heart by his mother-turned-parasite, Shinichi survives only through Migi's efforts. After regaining consciousness, Shinichi is devastated by the realization that none of it had been a dream.

Thinking he'd found his mother's killer, Shinichi instead meets Uda Mamoru, a man in a similar situation as himself. Uda sympathizes with Shinichi and suggests that they all work together. The time to avenge his mother has come at last! Shinichi heads to the precipice...

Shinichi has regained some semblance of a normal life. However, with Migi's cells dispersed throughout his body, his physical abilities have greatly increased to the point that not even Mitsuo poses a threat. Shinichi fears that the changes go beyond the physical and into the psychological. Just as peace returns to his school, a new parasite appears!

The divide between Shinichi and Satomi continues to grow. Shinichi's classmate, Yuko, investigates Hideo and unknowingly stumbles upon a dangerous secret. Meanwhile, Ryoko Tamiya, now known as Reiko Tamura, plots behind the scenes

The confrontation between Yuko and Hideo comes to a gruesome head when Hideo goes on a rampage throughout the school. With Satomi missing, Shinichi must hurry and find her before Hideo can get to her first.

Kana's interest in Shinichi transforms into full-blown obsession when she discovers that she is able to sense his presence. Little does Kana know that it isn't Shinichi she can sense, but something much, much darker.

Kana's special ability is gaining in strength. Believing that ignoring her will only endanger her life, Shinichi tells Kana everything about the parasites. Shinichi only wants to save Kana, but Kana believes Shinichi is lying to her. They are two ships, passing in the night...

A few days after Kana's death, things seem to be back to normal for Shinichi. Satomi and her friends are perturbed by his seeming indifference, but Shinichi, himself, is grappling with his own sense of disquiet with his unnatural state of mind. Meanwhile, a man begins snooping around about Shinichi...

Shinichi's secret becomes known to Kuramori, the private investigator hired by Tamura. Shinichi tries to confide in Satomi, but his unsuccessful attempt only drives a wedge between them. Shinichi recruits Uda's help to break the impasse.

Though still full of doubt, Kuramori has, for the time being, accepted Shinichi. Soon after, Kuramori's resolve is severely shaken by witnessing a parasite murder a human being. Shinichi is frustrated by the turn of events, but the lull is cut short when a new parasite appears...

The newest parasite to appear is different from the others. Chatty and expressive, the parasite identifies himself as Miki and immediately makes his move. With Migi asleep, all Shinichi can do is to run and keep running...

After Reiko's judgment is called into question, three members of her own group seek to eliminate her. With Reiko otherwise occupied, Kuramori takes advantage to seek revenge for his family.

Shinichi and Migi arrive at the park, only to find Tamura holding her child. As Shinichi struggles to quell his fury at the sight of her, Tamura unleashes a flurry of questions about the meaning of the parasites' existence and what humanity means to them.

Suspecting Shinichi's connection to the parasite cases, Hirama arranges to have Shinichi meet with Uragami, a convict with a peculiar ability. Although cleared of any suspicion and able to return to his high school life, it isn't long before Hirama appears once more before Shinichi. A government operation to neutralize the parasites with Hirokawa is about to begin...

The joint operation by the police and the strike force to eliminate the group of parasites led by Hirokawa has begun. Yamagishi's unit uses their special sensor system to hunt down the parasites. Amidst the chaos, human victory seems all but confirmed. But the tables are about to be turned by a single parasite...

In the chaos of the raid, Gotou escapes and vows to return to kill Shinichi. Plagued by fear and with nowhere left to run, Shinichi turns to Satomi for comfort.

Motivated by Satomi to stay alive, Shinichi resolves to fight Gotou. With Migi's support, they press their attack in an isolated forest. However, they fail to finish Gotou at a critical juncture, causing Shinichi to lose Migi and flee in defeat.

With Migi no longer at his side, Shinichi attempts to take on Gotou by himself one final time.

With Gotou's defeat, Shinichi's life is finally back to "normal." Though saddened by Migi's sudden departure, Shinichi moves forward with his life. However, a final threat appears...