Something that throws me off in every manga is the different societal expectations.
I read manga because I like stories, and the differences in view.
But isekai, in particular, really throw me for a loop; societal expectations are so radically different on our planet, so them being the same in different worlds? Like... cool story, I guess?
One of the big ones that throw me off is the notion of not helping in any way unless asked or given permission. That's normal, outside of the USA; I've been to Tanzania, and it's normal to just help there, as well.
But I know, I KNOW, that it's not normal in most societies, but... it still throws me off when characters in a book or novel dither over helping somebody else because they are "not supposed to" without being asked or told; Americans get a lot of crap for this, when abroad... still seems wrong to not automatically help other people... lol...