I'm not a big fan of Japanese chisels so I'll play "angel's advocate" (since David is playing "Devil's advocate") and give the reasons I don't like them.
A Japanese chisel is made from a layer of medium carbon steel, with a backing of very low carbon steel - so low that the backing will not harden with heat treatment. The carbon steel in a Japanese chisel is similar to the carbon steel in older western chisels, such as Witherby, et al.
When heat treating carbon steel, there are two major aspects of the final product: hardness and toughness. Hardness is the ability of the steel to maintain its shape without deformation. Toughness is the ability of the steel to absorb shock without fracture. Hardness and toughness have an inverse relationship - that is, if you make regular carbon steel harder, it is not as tough. If you make it very tough, it will not be as hard.
The steel in Japanese chisels is made harder (through heat treatment) than western chisels and the iron backing is used to make the overall chisel tougher - so the chisel itself will not break if stressed in certain ways. While the iron backing provides this advantage for the overall tool, the edge does not have any backing and is just carbon steel. This is the reason that Japanese chisels should not be sharpened to as acute an angle as many western chisels are sharpened to - while a western chisel might be sharpened to a 25* angle, the Japanese chisel should be sharpened to a 30-35* angle in order to reduce edge chipping.
The harder the steel is made in a Japanese chisel, the longer the edge will last but the more likely it will chip. Some Japanese chisels are made with the edge steel less hard (closer to the hardness of western chisels) and those edges are not as likely to chip. But if you're going to soften the edge of a Japanese chisel, you could just as well use a western chisel. So the net is that hardness/toughness is a tradeoff.
I'll note here that laminated chisels and plane blades were made in the west in the 18th and 19th centuries (and probably before that) by laminating a steel edge to a wrought iron body. If an extremely hard edge was of value in western woodworking, our western ancestors would have begun producing the tools that way.
All the Japanese chisels I've used have been too hard and it was too easy to chip the edge. And when you chip the edge, you have a big sharpening job on your hands, not just some honing.
When I talk to people who are Japanese tool advocates, they always have reasons for my bad experience with the tools. If only I would buy xyz Japanese tools, I'd have an outstanding experience with the tool and would be converted. But so far, no conversions have occurred for me.
The other thing I don't like about Japanese chisels is the handle. Japanese chisel handles are hooped and the end of the chisel is uncomfortable in my hand when I'm using the chisel with hand pressure (not striking it with a hammer).
My preference in chisels is for a western chisel with a socket handle so that I can easily make my own handles for the tools. So far, my favorite chisels are older western chisels, such as Witherby, Swan, DR Barton, and New Haven Edge Tools, and the LN chisels as new chisels.
Personally, for someone who has only had experience with Marples blue handle chisels, I'd recommend (as I did above) the older western chisels and the LN chisels before I'd recommend spending the large sums required for name brand Japanese chisels.
Once you have more experience, you should try Japanese chisels just so you know what they are and their advantages and disadvantages. But I do not recommend them as a beginning set.
Mike
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