Sorry, inverted is probably not the right word. I mean concave, like hollowed out. It looks a bit like that on the photo. It works at first, but is not good over time.

This is what I mean:
1 - better not
2+3 - ok, depending on purpose
4 - japanese, basically the same as 2+3
5 - might as well go all the way for 6
6 - best

6 is, however, taking the most work and time to do. But it pays with stability and lasting sharpness.