‘The Military Mirror of Kai’: Swordsmanship and a Medieval Text in Early Modern Japan

Swordsmanship emerged as a new field of knowledge in early modern Japan (1600–1868), a time of relative peace. During the most violent periods of Japanese history, the latter half of the medieval period (1185–1600), samurai conducted warfare mostly on horseback, using the bow and arrow, or by leading massive armies filled with soldiers who used pikes, halberds, and even firearms. In this paper, I will trace the origins of early modern swordsmanship to the late 16th century during the transition between the medieval and early modern periods, when teachers of swordsmanship and their sword ‘styles’ first appeared in texts. Of these texts I will focus on ‘The Military Mirror of Kai’, purportedly written during the late 16th century, and a widely-read text among samurai of the early modern period. A mix of fact and fiction, the ‘Mirror’ became a source of fantasy and inspiration for samurai and non-samurai alike. It is also the earliest source of writing about swordsmanship, which was influenced by, and grew alongside, other medieval cultural arts such as Noh theater and tea ceremony