Signed with 石原兼忠 
This sword was forged by Ishihara Kanetada, a Japanese swordsmith from Seki City, Gifu Prefecture, known for working in the tradition of the Kanefusa school. His blades are noted for their solid construction and clean, practical style, often echoing the aesthetics of Showa-era military swords.
After the World War II, Kanetada ceased swordsmithing, making his surviving works relatively rare and historically significant. 
This particular piece features non-standard, privately commissioned fittings, including a flat-style custom kashira (pommel cap) and a non-military tsuba, suggesting it was tailored for a specific individual rather than mass military issue.