Katana by Ishidō Unju Korekazu, seventh master of the Ishidō house of Edo, in Musashi province, and official swordsmith to the shogunate. According to the original seller, he was the son of Chōunsai Tsunatoshi, was born in 1820, entered the Ishidō house in 1841 and died in 1891; he forged blades offered to the Ise shrine and to Nikkō Tōshōgū, as well as swords presented by the shogunate to the United States (1854) and Great Britain (1859). The blade, with a nagasa of 84.6 cm and a sori of 1.5 cm, is shinogi-zukuri with iori-mune and chū-kissaki, long and with restrained curvature, with bō-hi on both sides. The seller describes a tight itame with mokume, ji-nie and chikei, and a gentle notare hamon with chōji, deep nioi, good nie and ashi, with a midare bōshi returning in komaru. The tang is ubu, with keshō-yasuri ō-sujikai, kurijiri and one mekugi-ana. The omote bears the signature and date 安政五年二月日 石堂運寿是一精鍛作之 (Ansei go-nen nigatsu hi Ishidō Unju Korekazu seitan kore o tsukuru), and the ura the owner's inscription 清和源氏白石時敏佩刀 (probable reading: Seiwa Genji Shiraishi Tokitoshi haitō). Gold-plated copper double habaki. The blade is kept in shirasaya. NBTHK Tokubetsu Hozon Tōken papers dated 8 April 2002.