What coarseness of japanese waterstones is ideal for cooking? Depending on the grit coarseness you can sharpen very blunt objects or refine an already sharp edge. Generally speaking, one can expect that a kitchen knife is much less heavily used than say, for example, carpenter tools or a pocket knife used to cut wood. I suppose for a kitchen knife there is no need for very coarse stones (say, below 200). Am I wrong here?
Oh absolutely, you certainly don't want to sharpen a kitchen knife on a 200 grit stone! You'll want one medium stone in case you ever need to remove a nick or something (but then you should probably take your knife to a pro at that point), and then probably like 2000-4000-6000 grits for routine polishing. (Note Japanese grit numbers are different than American oil stones).