Single-ply Hinoki 10 mm square blade. Exclusively made in Japan.
(Kaku = square) Any lines on the blade are characteristic of Hinoki wood. They are neither cracks nor signs of glueing/bonding. These are single-ply blades, made of pure HINOKI and each surface is very unique. Darker never glues pieces of Hinoki together but uses glue only to attach the grip pieces to the blade. Hinoki is a very fragile material. Very weak under the strong impact. Even with the rubbers, if you place the blade too roughly on the table it could possibly crack. That is why many Japanese users always carry spare blades, just in case. Handle with care.
