Genroku Shintō — The Forging Style of Japan's Peak Aesthetic Era

Genroku Shintō, as a technical designation, refers to the forging style centered on the Genroku–Kyōhō era (1688–1736), representing the third major phase of the Shintō period following Keichō Shintō (1596–1615) and Kanbun Shintō (1661–1673). While the existing category "Genroku sword culture" addresses social and cultural context (the peaceful society, Hon'ami appraisal, and the popularization of sword connoisseurship), Genroku Shintō as a forging style focuses more narrowly on technical and stylistic dimensions—hamon design, jihada treatment, and blade construction methodology.

The stylistic core of Genroku Shintō lies in the "apex of hamon decorativeness." Keichō Shintō had established bright, brilliant beauty as its foundational aesthetic in both jihada and hamon. Kanbun Shintō developed this into composed elegance—well-proportioned chu-kissaki and balanced hamon with clear structure. Genroku Shintō advanced further along this trajectory, pursuing bolder hamon variation and the intricate decorative effects of sunagashi (sand-grain patterns), kinsuji (golden lines), and complex interactions of nioi within the tempered zone. The "hamon interior activity"—the ornamental features such as sunagashi and kinsuji appearing within the hamon—became the foremost technical highlight of Genroku Shintō, particularly as mastered by the leading Osaka smiths.

The tōranba—a hamon featuring large, billowing undulations—pioneered by Tsuda Echizen-no-kami Sukehiro (1637–1682, with his peak activity in the Kanbun–Enpo eras) was the most important aesthetic innovation driving Genroku Shintō. The tōranba displays large undulating waves with dramatic amplitude; the crests are filled with complex combinations of nioi and nie. This hamon possessed the most visually dramatic effect, exerting strong influence on both Osaka and Edo smiths from the Genroku era onward. Sukehiro's blades commanded the highest market prices during the Genroku period, establishing "brilliance within the hamon" as one of the most important evaluation criteria in subsequent sword appreciation.

The Edo Kotetsu (Nagasone Okisato) lineage carried the forging style characteristic of Edo during this period. While Kotetsu himself reached his peak during the Kanbun era, his successors inherited through the Genroku–Kyōhō period the distinctive Edo aesthetic of "strong, refined jihada and deep nie." Blades from the Kotetsu lineage, in contrast to the decorative hamon of Osaka Shintō, tended to compete through the texture and depth of the jihada rather than hamon complexity. This east-west contrast shaped the diversity of Genroku Shintō.

A notable formal feature of Genroku Shintō is the fullness of hiraniku—the convexity or "flesh" of the blade from ridge line to edge. Whereas Keichō and Kanbun Shintō blades typically display relatively lean, well-proportioned cross-sections, Genroku Shintō blades tend toward richer blade profile with more pronounced convexity, increasing the three-dimensionality of form. This three-dimensional quality enhanced visual richness and represents a deliberate stylistic choice responding to the demand for Genroku-era sword connoisseurship (appreciation and collection).

The compilation of the Kyōhō Meibutsu-chō (1719) coincides with the height of Genroku Shintō style and marks an important cultural event. This named-blade catalog, compiled under the command of Tokugawa Yoshimune by Hon'ami Kōchū and others, comprehensively recorded and evaluated masterworks of both ancient and Shintō blades, representing the institutional summit of sword appreciation culture in the Genroku era. After the Kyōhō Meibutsu-chō, sword evaluation became organized around the criterion "whether recorded in the Kyōhō Meibutsu-chō," and the connoisseurship framework established during the Genroku era persisted throughout the late Edo period.