apanese steel is so good because of the precise alloying process. The Japanese are known for their rigor with quality control and making sure every finished product has consistent lines and polished edges.
With a high-quality raw material, regular checking (whether in or out of production), and lots of time, knowledge, energy, skill and patience invested in them at each stage - from refining right up to decoration - it's little wonder that you'll find this permeating through any blade made in Japan.