Kaiu Mizumi

Kaiu Mizumi is a swordsmith of the Crab Clan. In 1159 Mizumi forged the Shogun's Sword for Kaneka, who had recently been appointed as Rokugan's first Shogun. To show support for Kaneka and swear fealty to him as their Shogun Shosuro Higatsuku, Akodo Ijiasu, Hida Hitoshi, Moto Chagatai, Kitsuki Remata and Yoritomo Kumiko shattered their wakizashi. Mizumi used the broken shards to forge a new sword despite the great difficulty of blending different steels.

Four Winds p.47