This Japanese tanto features a blade length (nagasa) of 27.8 cm with a hira zukuri shape. The blade is in good condition. The blade is signed by Izu no Kami Sadayasu. Sadayasu (定保) was a distinguished Japanese swordsmith active during the Kōka era (1844-1848) in the Musashi province. Born into the Tsubouchi family, he was known formally as Tsubouchi Izu no Kami Fujiwara Ason Sadayasu and held the rank of Jū go’i, the fifth court rank. Apart from his duties as a hatamoto (a direct retainer of the shogun) and briefly serving as the castellan of Sunpu Castle, Sadayasu crafted swords as a pastime. He trained under Hosokawa Masayoshi and resided in Edo. His works are described as “very elegant/refined” in the 1857 publication Shintō Mei Shūroku.

The handle (tsuka) is wrapped in silk brocade. The menuki feature the Horu family emblem. The tsuba is iron, unsigned, with a slightly raised edge in mokko form and geometric patterns in gold tint on the edge. The fuchi-kashira are iron with gold plating. The blade collar (habaki) and washers (seppa) are not described.

The kozuka is iron and gold plated with a blade signed. The saya (scabbard) is gold and black lacquer, inlaid with Chinese porcelain coins. The kurigata depicts a demon head in iron.

This tanto is noted for its elegant craftsmanship, featuring a good condition blade and finely detailed koshirae. It was part of the Koller Auktionen in December 1992 and previously belonged to the Albert Polster collection.