The great legacy of blade technology in Japan and the requirement for precision carving in the production of Ukyo-e prints gave rise to the development of carving tools such as these. Crafted from a high-quality two-part steel: a high carbon steel which holds the cutting edge, laminated to a softer steel which provides strength with a little flexibility to help prevent breakage. The tools leave the factory very sharp so please take care when handling.
They are designed with a long blade that as it is sharpened down can be moved forward within the handle:
For U and V gouges do this you by removing the brass ferrule to splay open the cherrywood handle. The long blade has a curved tip on the back end that can be pressed back into the wood one it is re-positioned. This stops it slipping back when carving.
For the Hangi-To blade, remove the brass ferrule and lift the blade up out of the groove in the handle. If the brass ferrule doesn't slide off easily then try prising it off with a blade under the long side of the ferrule, or wrap the ferrule in a cloth and gently prise off with pliers.