I've looked into getting some Japanese kitchen knives for quite a while--along the way I've learned a few things.
I've also seen the cutting board results that Josh mentioned. I seems that everybody just assumed that plastic was "safer", but no one ever bothered to count what actually could grow on the boards--less grew on a wooden board.
The traditional handles are force-fit onto the tang. They are, with dificulty unless loosened with wear, replacable. That was done on purpose, a well-made blade will out-last the handle. Such handles are put on several-thousand dollar knives. And the particular type of wood used is very durable and water resistant, though is is a little soft compared to many hardwoods. On the one such inexpensive knife I have, I sanded the handle, and oiled it, sort of as an experiment, also because I didn't like the way it was darkening with use. There are some subtle highlights and it is quite attractive. If the handle is properly fitted and the knife maintained, I don't think sanitation is a problem--who is more picky than the Japanese about sanitation, especially when paying big $$ for raw fish? They've been using just this wood for just this purpose for a long time.
Super-expensive traditional knives may be made from a single piece of very hard carbon steel. They are hard to make, hard to sharpen, and ususally have the traditional single bevel/grind. Unless you're a master sushi chef with a couple thousand to blow and a complete set of high quality water stones, you probably won't be using one. I imagine that they are somewhhat fragile as well.
Two-layer laminated blades with one side soft (best is apparently old, genuine wrought iron) and one side very hard are single bevel/grind. They are easier to sharpen and come in many levels of quality depending upon materials and the degree of hand-work, and of course who did the handwork.
Three layer (sandwich) lamination with two soft layers enclosing a inner hard layer will, by necessity be ground on both sides--how else to expose the inner layer to take the edge? There may or may not be a secondary bevel, which could be symmetrical or applied only to one side. With honing that small secondary bevel could be centered or even moved to the other side, though the difference would likely be miniscule. These come in a variety of quality and price, and this is where one sees layered steel or damascus used for the outer layers. Carbon outer, carbon inner, SS outer, carbon inner, and SS outer, SS inner all are on the market.
So are SS alloy non-laminated blades produced from modern "high-tech" steels.
Western shapes and traditional Japanese shapes are available, and western style full-tang handles with riveted slabs are available.
Of course, there is a japanese term for every permutation.
"Hard" can mean anything from Rockwell 59 up to Rockwell 64 (!). A decent set of waterstones is likely needed to get the best out of the latter. A "quick touch up" on a ginder or belt sander would probably cause significant damage or chipping.
The bewildering variety of shapes and names can be confusing--make sure that the knife matches the intended use. Some names reflect construction, or material, some intended use, and some region of origin since different areas have produced slighty different shapes for the same job. And some are very specialized--on a now apparently defunct website I saw a regional knife that was specifially intended for processing eels, from push-cutting off the head to slicing. (I suspect that knives of this type may be the "inspiration" for some of the otherwise seemingly useless shapes of "tactical" blades) There is also an enormous sword-like knife for the initial processing of 1,000 lb tuna.
Chopping on a chicken bone will ruin a thin delicate veggie slicer or a knife intended to slice raw fish meat. As would steeling like the kid in the deli does. The toughest Japanese kitchen task I know of is cutting trough the backbones of large fish, or boning (not chopping!) fowl. The knife called a deba or deba-hocho is stong and very thick and is used for the large fish.
Great store is put into slicing or push-cutting the food so as to cause the least amount of tearing, mashing or release of juices, as this is thought to adversly alter the tast of the food. I'm no expert, but I am not aware of chopping as we think of it in the West being used for any traditional Japanese cooking. I'm likely wrong, there probably is some exception, but the idea of wacking a couple of onions on a board with a heavy 14" knife just doesn't occur to them, as can be seen from the lack of such tools in the traditional kitchen implements.
This site has a nice collection of imported Japanese knives most of which are accessably priced factory-made knives that are, I think well-chosen for Western kitchen use. Bevel-type is double, unless otherwise noted. I have visited the store, and the owner chatted with me an my brother for over an hour as we looked at the kitchen knives, though we didn't intend to purchase any that day. It was very informative, and I think that he would be happy to help anyone select a suitable knife by e-mail, and would tell you what didn't fit what you wanted to do. He also had a small catalog that covered the kitchen knives that provides more information than is on the website--I bet he would mail out one. The other knives on his site, all customs, are fun to drool over as well, and the ones that we saw in person were amazing.
http://www.bladegallery.com/knives/type.asp?code=qkitchen&display=Knives+for+Chefs
FWIW, the ones there by Kobayashi to me and my brother to be a good selection--
reasonable, price, ferrule is forge welded to tang (OK, no "handle-problem"), familiar Western shape, very light and thin with good feel and taper. and though SS, the center is Swedish tool steel at Rc 62. The handle is a bit clunky, as the owner immediately pointed out, but it felt better than the similarly or less espensive knives without ferrules. He offered to grind down the handle to a better shape and buff it for an additional $20, as I recall, and said that he often does this.
Whew, that was long, and I'm too lazy to correct the typos.
