山鹿素行

Yamaga Sokō (1622–1685) was the foremost military theorist and philosopher of bushidō in Edo Japan. Trained from age nine under the Confucian scholar Hayashi Razan, he systematized the Yamaga school of military science (heigaku), which treated martial strategy and moral philosophy as inseparable. His treatise Shidō (The Way of the Samurai) established the philosophical framework that defined the samurai's social role — not merely as warriors, but as moral exemplars bearing the sword as a symbol of ethical responsibility. Exiled to Akō domain in 1665 for his heterodox Confucian views, he taught the Yamaga school there; his disciple-in-spirit Ōishi Kuranosuke, leader of the forty-seven rōnin, embodied his teachings in practice. Sokō's work is the direct precursor of Nitobe Inazō's modern Bushido — the intellectual foundation of Japan's most celebrated martial ethic.