That whole speaking in a high voice is just Japanese pop culture, bros. They emulate what they saw on their popular media, anime etc. It ain’t about upbringing and shit.

It’s the same thing that drives their cosplay culture. They were not brought up being taught how to dress like a female succubus. They’re just emulating popular anime characters.

I personally have only met 2 J girls that spoke in a high voice like that in all my time punting, so I wouldn’t say they are a common occurrence here.