Additionally, in normal Japanese companies that 6M _is_ the senior salary with starting salaries around the 3M~4M range. A 10M salary is basically a non-starter right off the bat at most places, they'd basically laugh you out the door with that, well, if you got a chance for an interview in the first place, but you wouldn't.

That said, 10M is of course not impossible, but in my experience it is mostly reserved for larger foreign companies, the banking sector or if you somehow manage to get to an executive level. And maybe a handful of very specialized very well funded companies.