Zen Buddhism in Japanese Swordsmanship: Shinmyōken and the Buddhist Layers of the Edo-Period Jikishinkage-ryū Transmission Texts

The association of Zen Buddhism with Japanese swordsmanship, often presented as natural, is in large part a modern construction. This article re-examines the relationship through one well-documented lineage, the Kashima Shinden Jikishinkage-ryū of the Edo period (1603–1868), asking how the concept of shinmyōken (“subtle sword of the mind”) functioned in the school’s transmission texts (densho) and how Buddhist symbolism entered them. Translated certificate lists (1696–1862), the Gokui-den, the Hōjō kokoro-e sho, a nineteenth-century travel diary, and Japanese reference works were analysed qualitatively, coding religious vocabulary by level of transmission. The densho prove to be layered: Taoist and Neo-Confucian cosmology frames the lower levels, whereas Buddhist symbolism becomes explicit only in the Gokui-den. Shinmyōken is paired with kōmyōken (“sword of action”) and names the conditioned mind from which action arises. The highest transmission combines the esoteric A–Un syllables, Fudō Myōō, fudōshin, and the ten evils, culminating in an empty-circle certificate. The Buddhist layer is thus syncretic—Rinzai Zen, esoteric, and Shinto—rather than purely Zen, and the densho can be read as lay Buddhist literature carrying the threefold training in the idiom of the sword. The article also considers the martial appropriation of this vocabulary and the nationalist politics of Ōmori Sōgen’s twentieth-century synthesis.