Ōkubo Nagayasu

Ōkubo Nagayasu (1545-1613) served Tokugawa Ieyasu as the first daikan-gashira (chief land magistrate), overseeing the management of the shogunate's directly controlled mines including Sado Gold Mine, Iwami Silver Mine, and Izu Gold Mine, generating enormous wealth. Said to have originally been the son of a sarugaku performer, he first distinguished himself as a financier serving Takeda Shingen before being recruited by Ieyasu. His achievements in supervising the extraction, refining, and distribution of gold and silver were pivotal in establishing the shogunate's financial foundations. After his death, suspicions of embezzlement triggered the 'Ōkubo Nagayasu Incident,' which brought ruin upon the Ōkubo clan. In sword lore he is said to have leveraged his mining interests to commission custom-made pieces from master smiths across the country, earning him a unique place in sword history as a figure who embodied the connection between mining and the sword world.