Which whetstone and grit should I buy for Japanese knives?

If you buy one stone, make it a 1000 grit: it sharpens a dull edge and is fine enough to leave a keen, kitchen-ready finish. A 400 grit handles chips and heavy reprofiling, and a 3000 or higher refines toward a polished edge once you are comfortable.

The community compares brands endlessly (Shapton Kuromaku, Glass, and Naniwa Chosera all have fans), and the videos below show those head to heads. The honest takeaway is that a flat, well-used 1000 from any reputable maker beats a fancier stone used carelessly.

Our K&S take: anchor on the in-stock Naniwa Chosera 1000 and add an Atoma diamond plate to keep it flat. We do not currently stock the Shapton 1000, so we will not point you at one we cannot ship.