Aoto is a natural medium stone you use between #2000 synthetic and #6000/8000 synthetic or natural medium finishing stone. It is possible to jump to #8000 from #2000, but it takes long time to erase the marks from #2000, and also you'd lose a lot of #8000 by fixing the flat of the surface.

Although synthetic finishing stones are fast in cutting thus very convenient for daily use, the marks that's incised are quite deep even with #8000, it takes lots of time to erase it with the finishing stone. So when I want to make the edge extra fine, I would switch to natural stones altogether after #2000, and use Aoto > natural medium finishing stone > natural finishing stone.

Sides lacquered. Aoto tends to split along the grain, so it is better if you reinforced it somehow. The best way is to wrap one thin layer of tissue paper, and then lacquer it. Then it will never split. But I just lacquer it couple of times.

Also, when you flatten the surface you have to remember to flatten the straigt grain side, and not the cross grain side like in case of finishing stone. In the case of this stone you can see the straight grain running diagonally.

When wetted.