A famous set of long and short katana forged by swordsmiths from Bizen province. Kanehira, who created the larger sword O—Kanehira, was one of three master swordsmen of the Kobizen school of sword crafting alongside Sukehira and Takahira, collectively known as the "Bizen Sanhira," or "Three Hiras of Bizen." Widely regarded as Kanehira's finest work, the sword's name was prefixed with the character for "great" ("o"). It became an Ikeda clan heirloom after it came into the possession of Ikeda Terumasa. The shorter sword, Uguisu—maru, was forged by the father of Bizen—style sword crafting, Tomonari. The faint olive green tinge, similar to the coloration of the Japanese nightingale ("uguisu"), heightens the sword's beauty, and many believe it to house ghostly powers.