Nanki Shigekuni is said to have originated in Yamato Province as a late offshoot of the school, the lineage of the celebrated Kanenaga. His common name was Kurosaburo. During the Keicho era (1596--1615) he entered the service of Tokugawa Ieyasu and forged swords at Sunpu in Suruga Province (present-day Shizuoka City), serving as a retained smith. Thereafter, when Ieyasu's tenth son Tokugawa Yorinobu was transferred to Kishu Wakayama in Genna 5 (1619), Shigekuni accompanied him and relocated accordingly. One tradition holds that he resided at the foot of Mt. Myoko. As a kakae-ko of the Kishu domain, he occupied a position of considerable prestige, and his second-generation successor -- known as Monju Shigekuni for the characters he customarily included in his signatures -- continued in this official capacity, reportedly serving as a forging counterpart for Yorinobu himself. The first generation's active period spans from the Keicho era through Genna, placing him squarely at the dawn of the age.
Shigekuni's workmanship may broadly be divided into two types. One is a in which is mixed with -- works thought to reflect his private admiration for the superior masters, and above all for Go Yoshihiro. In these pieces the is deep, adheres thickly, and conspicuous and reveal a pronounced coloration. The other type is a that inherits the Yamato manner as what the consistently terms his "family specialty," evoking Kanenaga. In either mode, his forging characteristically shows a flowing mixed with , with thickly applied and abundant ; within the tempered edge the is likewise strong and stand out. A construction featuring broad and a high is typical. His tends toward with vigorous and a shallow . The presence of , , and along the signals his Yamato inheritance even within - works. A distinctive hallmark is the appearance of within the temper forming whorled, spiral-like configurations. On , conspicuous is noted as a distinctive feature of his construction. Critically, Shigekuni's achievement lies not in simple imitation but in what the describe as establishing "his own distinctive style" by taking - as the foundation, adding Yamato elements, and forming a personal idiom upon that base.
Above all, the quality that the identifies as the true essence of his art is the brightness and clarity of both and -- a phrase rendered consistently across his designations as "the is bright and clear" ( and ). This luminous quality, combined with the thick and the conspicuity of and , allows one to perceive what the examiners describe as "the very essence of his art." His finest works are praised as displaying these strengths "without reservation." The further notes that nearly all of his - survive in condition for reasons not entirely clear, rendering examples with extremely rare and of high documentary value. Several of his - bearing the Genna 8 date carry ownership inscriptions of Yorinobu's chief retainers, providing valuable material for research. The also observe that Shigekuni's - idiom shares something in common with the later style of Batetsu, suggesting that Batetsu took such works "greatly into consideration" -- a testament to the documentary significance and formative influence of Shigekuni's achievement within the early tradition of Province.