切刃貞宗

The question of Sadamune's parentage — real son or adopted son of Masamune? — has been debated for seven centuries and remains unresolved. But in a culture where bloodline authority permeated every art and craft, the claim that Sadamune carried Masamune's blood gave every blade he forged a sacred weight: to own one was to hold the closest possible link to the divine originator of the Sōshū tradition. The Owari Tokugawa lords, who assembled one of the greatest sword collections in Japanese history over three centuries at Nagoya Castle, placed Kiriha Sadamune at the summit of their holdings — a position it still occupies at the Tokugawa Art Museum. The blade's kiriha-zukuri construction, which solves the contradiction between cutting sharpness and structural strength in a single asymmetric cross-section, is itself a lesson in the Japanese principle that the deepest beauty arises from the perfect integration of function and form.