Can Jap Isekai Novels send their MC in a world that is not inspired by Fantasy Medieval Europe?

I've seen a few where, as you said, they get isekai'd into ancient japan instead. I just think that a) they're not being translated that often here on NU and/or b) there's way more RPG isekai than there are those, mostly with game elements. To be honest, I hope they make shit more realistic/interesting and less of a power trip for the author, or this isekai trend dies down. 

Throws Twelve Kingdoms and runs away. 

Yeah, that's usually the way to go.
The thing is that if you wanna work with the author of a novel, you have to start from the first chapters unfortunately. Otherwise they'll get confused, then there will be trouble over publishing rights etc...
Anyway, it's a major pain. 

It’s not the authors’ fault. It’s just that only truck-kun has the power to decide where the MCs are sent. This is the risk that all authors have to take when they decide to write an isekai novel, they have no idea what kind of world their novel is going to have and everything is as dictated by truck-kun. Authors can only take over the story after truck-kun finishes his job.
There are even times when authors don’t want to write an isekai novel but then truck-kun keeps reappearing no matter how many times they decide to rewrite... 

Then you get death march 90% food arc and 10% story/action.