Driving through the valleys outside Hofu in Yamaguchi Prefecture, Yasha Yukawa scours the surrounding rice paddies for the raw material he covets. He is constantly on the lookout for rice straw, but only the farmers that harvest the traditional way preserve it.

"The people who live there harvest by hand," he says, pointing toward a house with a paddy where last year's stems are still poking out of the ground. "But they give their straw to the local Shinto shrine for making shimenawa, the rope enclosing the sacred space."

Yukawa requires a paddy field's worth of rice straw a year to help make his swords. He burns the straw slowly, one bundle at a time, so that important qualities are not lost. The straw ash and clay are used to form a protective layer around the steel while it is heated.