Teenage years, but if it starts this young where will the main character be in his teenage years? He is being led down a dangerous road. Right now, he is being taught how to be manipulative. What he has been listening to has are a affected him. He is having bad dreams. Everyone has their own way and opinions. For me I would avoid this type of person.
But as you said before, he's a kid himself. He didn't even aware if he's being manipulated by that one friend. I don't even think that one friend even aware of what he did LOL. That's why some readers demand the mangaka to tell about that one friend family background cause either this kind of behavior is in his blood like he's born with it or simply he just copied the adult around him... But i don't think the mangaka would take a dark turn with him, idk tho ╮( ̄▽ ̄)╭
I don't like the new character. I believe he is a bad influence on the main character. His presence is making the story less fluffy and more uncomfortable to read.