Kiseijuu: Sei no Kakuritsu - Season 1

Shinichi Izumi's life takes a turn when a creature called a Parasyte attempts to infiltrate his body in order to take control of it, but it ends up burrowing into his right hand and both are forced to cooperate.

Shinichi and his Parasyte, now named "Migi," battle for control of Shinichi's arm as the number of Mincemeat Murders increases. But when an encounter with another Parasyte turns hostile, they must work together if they hope to survive.

Also known as "Symposium." Sinichi and Migi come across two more of Migi's kind - one, a new teacher at Sinichi's school named Ryoko Tamiya, has the ability to keep a low profile and adapt; while the other is an evil creature who will continue to kill humans mercilessly until the day he dies. He sees Migi as a threat to his livelihood that must be taken care of immediately.

While Shinichi and Migi are learning to work together, Shinichi's relationship with his parents (especially his Mother) is becoming more distant and strained.

A violent confrontation with a gang brings Shinichi face-to-face with a girl named Kana, who begins to take an interest in him. Shinichi's parents continue their vacation, but their trip is cut short by an unexpected attack.

With Shinichi at the brink of death, Migi takes drastic actions to ensure his host's survival. After a trying recovery, Shinichi learns that his father is still alive and races to his side before the Parasyte that attacked his mother strikes again.

Shinichi sets out for revenge and runs into an unexpected ally. Together they team up to take down the Parasyte that brutally attacked Shinichi's family. But when Migi falls asleep, Shinichi is forced to engage the enemy on his own.

Life has returned to normal, but Shinichi has not as his ties to Migi continue to change him. As those around him grow wary of this 'new' Shinichi, a Parasyte named Hideo Shimada emerges from the shadows and begins attending Shinichi's school.

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.

Shinichi is trying to discover how many parasytes are in his city. Shinichi tells Kana the truth about himself and his Parasyte but she does not believe him. However, her obsession with him leads her to disaster.

Shinichi goes back to the site of Kana's death, he does not want to loose the ability to feel sadness. There he is seen by a detective and his parasyte tries to kill the reporter.

Shinichi confronts the detective and explains the situation to him.

Kuramori has his doubts about Scinichi while tagging along with him. Shinichi soon goes from the hunter to the hunted while Kuramori watches.

Shinichi is attacked by a parasyte unlike any he has seen before, he runs away after fighting a intense battle. Meanwhile Kuramori puts his family in jeopardy with his search for the truth.

Once Reiko's judgement is called into question, three members of her own group try to eliminate her. While Reiko is occupied, Kuramori uses the opportunity to seek revenge for his family.

Reiko tells Shinichi some things that she has discovered about Parasytes and Humans, then gives her baby to Shinichi. This causes Shinichi to have flashbacks to his parents. He then meets another man who is able to sense things.

Shinichi returns to school, Shinichi is asked about firepower that may be effective against parasites, Uragami reflects on why he can sense the parasytes.

The police start their operation to take out Hirokawa and the remaining parasytes. Plans go awry when the Parasytes try to fight back. Things get more gruesome when Gotou appears.

Gotou escapes during the chaos of the raid vowing to return and kill Shinichi. Shinichi is plagued by fear and with nowhere left to run he turns to Satomi for comfort.

Schinichi and Migi come to a showdown with Goto and Migi formulates a plan to leave Schinichi.

Schinichi has a showdown with Gotou and then comes to a decision.

After Migi says a final farewell, Shinichi tries to return to normal, until an unexpected enemy returns.