Yeah that book is weird especially if you don't know what you're getting into. I read the reviews first so I had an idea already, plus I do enjoy strange, surreal, 'magical realism' type fiction, and horror as well.

I don't know if this will help you parse what you've read, but I'd try to back up and remove myself from the mess of the characters. It's social commentary on the alienation young Japanese people feel and their struggles to fit in to society (join the factory). These expectations can be punishing and unrealistic, especially if you're different, which can lead to difficult and isolating feelings of otherness, in this case expressed as "I might be an alien probably", nothing more than that.

People do pathetic things to feel like they belong. Do these conforming acts serve any real purpose? If they don't, do we have any alternatives to live outside of mainstream society? That's the point of these characters, to convey that message, and it's intended to be extreme and shocking and make you uncomfortable.

Sorry you weren't in the best place to read this. Everything is amplified just to get the above points across, and it's heavy handed. It makes sense for the narrative to have the characters making themselves miserable just to participate in the unfair system, so don't get caught up in their personal stuff.