Shodai Echizen Yasutsugu was born in Shimosaka-gō, Sakata District, Ōmi Province, where he styled himself Shimosaka Ichizaemon. He later moved to Echizen and entered the service of Yūki Hideyasu. In his early phase he signed "Higo Daijō Shimosaka," but between Keichō 10 and 11 (1605–1606) he was summoned to Edo, where he forged swords in the presence of both shoguns Ieyasu and Hidetada. In recognition of this distinction, he was granted the hollyhock crest (aoi-mon) and the character yasu, after which he adopted the name Yasutsugu. This direct patronage by the Tokugawa house placed him among the most politically elevated smiths of the early shintō period.

His forging is characteristically dense itame-hada mixed with mokume, exhibiting extremely fine ji-nie and well-entering chikei; overall the steel tends toward a dark tone, producing what is termed Echizen-gane. His hamon is typically based on a medium suguha or shallow notare, accompanied by linked ko-gunome; ko-ashi enter well, nie adheres thickly, and fine kinsuji and sunagashi appear in places. The nioiguchi frequently shows a shizumi tendency, lending a deep, savoury quality. His bōshi commonly rises in a suguha tone with a pointed tip in a Jizō-like manner, with vigorous hakikake and a long turnback. Notably, his finest works display a tightly forged ko-itame of excellent quality with a bright nioiguchi, departing from the more usual standing grain. His horimono are deeply cut and forceful, rendered in characteristic kinai-bori, with triad compositions of Fudō Myōō with the two dōji attendants appearing as a signature motif.

Shodai Yasutsugu occupies a foundational position in the Echizen tradition and among the official smiths of the Tokugawa shogunate. His works combine the powerful, dignified sugata of the Keichō era — wide mihaba, thick kasane, and elongated proportions — with a subdued depth of nie and surface activity that rewards close appreciation. His distinctive steel quality, intentional variation of tempering patterns, and superb sculptural carving together distinguish him as one of the preeminent smiths of early shintō swordmaking.

Shodai Echizen Yasutsugu was born in Shimosaka-gō, Sakata District, Ōmi Province, where he styled himself Shimosaka Ichizaemon. He later moved to Echizen and entered the service of Yūki Hideyasu. In his early phase he signed "Higo Daijō Shimosaka," but between Keichō 10 and 11 (1605–1606) he was summoned to Edo, where he forged swords in the presence of both shoguns Ieyasu and Hidetada. In recognition of this distinction, he was granted the hollyhock crest (aoi-mon) and the character yasu, after which he adopted the name Yasutsugu. This direct patronage by the Tokugawa house placed him among the most politically elevated smiths of the early shintō period.

His forging is characteristically dense itame-hada mixed with mokume, exhibiting extremely fine ji-nie and well-entering chikei; overall the steel tends toward a dark tone, producing what is termed Echizen-gane. His hamon is typically based on a medium suguha or shallow notare, accompanied by linked ko-gunome; ko-ashi enter well, nie adheres thickly, and fine kinsuji and sunagashi appear in places. The nioiguchi frequently shows a shizumi tendency, lending a deep, savoury quality. His bōshi commonly rises in a suguha tone with a pointed tip in a Jizō-like manner, with vigorous hakikake and a long turnback. Notably, his finest works display a tightly forged ko-itame of excellent quality with a bright nioiguchi, departing from the more usual standing grain. His horimono are deeply cut and forceful, rendered in characteristic kinai-bori, with triad compositions of Fudō Myōō with the two dōji attendants appearing as a signature motif.

Shodai Yasutsugu occupies a foundational position in the Echizen tradition and among the official smiths of the Tokugawa shogunate. His works combine the powerful, dignified sugata of the Keichō era — wide mihaba, thick kasane, and elongated proportions — with a subdued depth of nie and surface activity that rewards close appreciation. His distinctive steel quality, intentional variation of tempering patterns, and superb sculptural carving together distinguish him as one of the preeminent smiths of early shintō swordmaking.