The Naniwa Professional line (previously known as the Chosera line) are super hard splash and go stones. These stones are slow wearing, fast cutting and HARD. They have a higher amount of abrasives and less binder than other lines from Naniwa, and are one of the best lines of stones money can buy in our opinion!
A 1000 grit stone is our first recommended stone in everyones kit, its coarse enough to cut in a relatively dull knife, and fine enough that with lightened up hand pressure you can polish your edge up enough to be able to shave your arm hair! Remember, if you can't achieve great sharpness on a 1000 grit stone, your technique needs adjusting, or you should have started on a coarser grit stone if your knife was already too far gone to be brought back to life on a 1000, before a higher grit stone will help you!