Special limited edition made only for my father. The BEST of the BEST Reigou blade. This model is not retailed even in Japan. Please see the detail photos in 70mm's page.
All Yokoyama plane blades are forged using pine charcoal. Charcoal smithing is the best because the low heat prevent the carbon evaporation. But at the same time it is the most expensive method as well, so not many blacksmiths forge this way.
Some blacksmiths claims their planes are charcoal smithed but in reality gas forge smithed.