holy shit the OEDIPUS COMPLEX. this is like a psychology gasm ngl. I see how sachi is like his mom. she's as unhinged as his mom was.
I also feel really bad for sachi. i tore up with her when she tore up. she might have some problems, but in terms of "brokenness", she's the least broken out of the other broken characters. her narcissism is an issue and how she wanted a relationship with punpun just to have him as her pet, but she wasn't genuinely malicious in her actions. she did help punpun, she's just a bit of a horny asshole. she's "normal" broken, compared to the fucked up levels of broken we have. I don't think she qualifies as a "massive" piece of shit.
the driving class girl was also a normal person (we know nothing about her though tbh)