This is a good example of the 3rd generation Yasutsugu.  The quality of this sword is very good and has no flaws.  It was a family sword that was mounted in WWII for the war.  It was mounted with an antique tsuba and antique menuki.  This is not common and adds an interesting detention to the mounts.  The blade has good activity and the hada/grain is very rich and dark looking. This sword is in full polish and is in a shirasaya.  The mounts are held together with a wooden tsunagi.  The sword comes with papers from the Nihon Tōken Hozon Kai (日本刀剣保存会) ‒ NTHK from Japan (Japanese sword preservation society).

Info on smith:
YASUTSUGU (康継), 3rd gen., Kanbun (寛文, 1661-1673), Musashi – “Yasutsugu nanban-tetsu o motte Bushū Edo ni oite kore o saku” (康継以南蛮鉄於武州江戸作之, “made by Yasutsugu with nanban-tetsu in Edo in Musashi province”), real name Shimosaka Umanosuke (下坂右馬助), he adopted later the first name Ichinojō (市之丞), son of the 2nd gen. Yasutsugu, he was not of age when his father died and so a succession dispute arouse which resulted in the splitting to an Edo and an Echizen branch of the Yasutsugu school, it was settled that both were allowed to call themselves 3rd gen., according to tradition he was fully trained by his uncle and he worked later for the bakufu, we know date signatures from the third year of Kanbun (1663) to the third year of Enpō (延宝, 1675), he worked in the style of the 2nd gen. but did not reach his quality, he signed the left radical (糸) of the character for “tsugu” in the variant (糹) and the frame of the right radical (米) in an angular manner (乚), jō-saku