It’s fucking messed up how some people, quite ironically, think that Naruko, the girl from the first story, was a heartless villain, when she was actually the only one who genuinely cared about Naoto. She simply wanted to get closer to him little by little. After all, Naoto was easy to manipulate, as we saw in the final chapters, where his mother started treating him well without even realizing why. Basically, the reason was that she had sold/prostituted her own son.
The reason Naoto’s mother indirectly started treating him better was because of the neighbor and the money she had given her. In the second chapter, she even mentions how angry she is and how her blood boils when she sees Naoto being happy after she had had a bad day. No sane mother would say that to her own son. Not only did she constantly mistreat him and treat him badly, but she also kept him dirty and didn’t even feed him properly. But a chapter where she treats him decently, and suddenly everyone goes crazy saying how she has changed and how she’s actually the good one.. That is precisely what is ironic and dangerous about a superficial reading: people mistake the effect of the money (and the control the neighbor exerts) for a genuine moral change.
Meanwhile, Naruko with all her problems, her darkness, and her twisted nature is the only one who consistently gives Naoto food, attention, a safe place, and something resembling affection. The rest of his family environment either used him or despised him. And I’m not just talking about his mother, but also the teachers who looked down on him and his “friends” who pushed him aside. If it weren’t for Naruko’s appearance, Naoto’s life would have been much, much worse, because his mother would have had no problem selling him or letting him starve to death, not to mention that Naoto would have continued to be rejected by everyone.