Chapter 10

Concern (こだわり, Kodawari) is the 10th chapter of the Parasyte manga series, written and illustrated by Hitoshi Iwaaki.

Overview
''When heading to school one morning, Shinichi notices Nagai getting jumped. Though Shinichi is beat up for trying to defend him, a girl named Kana convinces her boyfriend and the rest of his gang to stop, and takes an interest in Shinichi.''

Summary
The morning after Shinichi's parents have left, he wakes up late and berates Migi for not waking him earlier. Migi tells him it didn't because his body needed the sleep. Since Shinichi is already late, he decides to take his time getting to school and thinks about how both his mother and Satomi Murano have said he's changed, although he has noticed no change in himself. He also recalls Ryoko Tamiya stating that he has something mixed in, which Migi suggests is due to their connection slightly altering Shinichi's brain and nervous system. Migi then goes to sleep and leaves Shinichi freaking out about it. He denies it to himself, stating that he has no desire to eat people.

As he walks he comes across a dirty bag and kicks it away before realizing he recognizes it. He then hears the sounds of a fight nearby and goes to investigate, recognizing Nagai who is being beat up by Mitsuo and his friends. Shinichi tries to convince them to stop, which only makes them laugh. One then punches him, which makes him begin to leave before he recalls a flashback to Migi expressing an inability to comprehend the human trend of altruism or self-sacrifice. This in turn prompts Shinichi to turn back, convincing himself that helping others even if he might get harmed is a human thing to do. Again, he tells the others to stop.

Mitsuo comes up, now irritated, and beats him up as well. Kana tells Mitsuo to stop but he continues, stating he hates "lying sons of bitches". He steps on Shinichi's right arm, which makes him worry about Migi waking up. Kana yells at Mitsuo to stop, stating he's wasting his time on someone like Shinichi.

She meets Shinichi's eyes and is startled back, imagery depicting the claws of a reptile closing around her. Mitsuo calls her away and Shinichi checks on Nagai, who calls him stupid. Shinichi mumbles that he did it because he is human.

At school, Kamijo asks after Shinichi and tells him that the students of North High are currently feuding with some of West High, Shinichi's own school. After school, Satomi also asks Shinichi about his bruises. Kana then shows up and questions why Shinichi didn't leave, then calls him not normal to Satomi. As Shinichi starts leaving with Satomi, Kana yells at him for pretending to talk about justice despite his dark interior.

Mitsuo later asks why Kana shows any interest in Shinichi, assuming that she hated pretend white knights. Kana agrees, but internally thinks that Shinichi seemed barely human. She then asks if Mitsuo is jealous, which he denies.

A few days later, Kana looks on in disgust upon seeing Shinichi and Satomi walking together again. Satomi is then grabbed and Shinichi sucker-punched by Mitsuo and his gang in an attempt to make Shinichi back down and show his true colors as a coward. As Shinichi tries to rescue Satomi, he is punched repeatedly by Mitsuo, but refuses to stop. Migi then wakes up and judges their strength, stating that Shinichi is badly outpowered by the others. Shinichi refuses to give up.

As he is knocked into a wall, Migi morphs into claws in preparation to attack, which Shinichi protests. Kana then walks up and berates Mitsuo before Kamijo, Nagai and a large group of fellow West High students show up and surround them. Kana flees, leaving the gang of North High members behind who are then beat up. Satomi goes to fuss over Shinichi and Kamijo tells them to go home.

Satomi cries, feeling guilty for Shinichi's wounds as they go to his house, and cleans him up. She notices that despite the rest of him being scuffed and bruised, his right arm looks perfectly fine. Later in the conversation, Shinichi wonders if he's different from the others and Satomi agrees, stating that he's cool and no one else would have stood up for that long. Shinichi invites her to spend the night and she promptly leaves. Migi expresses disappointment at being unable to observe human mating.

Kana wonders what Shinichi is, if he's not just acting to hide his own weakness.