Kansuke Yamamoto

A military strategist of the Muromachi period. Also known as Haruyuki, his Buddhist name was Nyudo Doki. He was born in Sanuki (Kagawa Prefecture). He went to Yamaguchi and served under Ouchi Yoshitaka, then became a ronin and served under Takeda Harunobu (Shingen). He excelled in military tactics and was highly valued as a military strategist, achieving outstanding results in military strategy, fortification, and drafting the Koshu Laws. On September 10, 1561 (Eiroku 4), he proposed the "Woodpecker Tactic" during the Battle of Kawanakajima between Takeda and Uesugi, and was heroically killed in the fierce battle. He is considered the founder of Koshu-ryu military tactics, and Kansuke's name was spread nationwide by the Tokugawa military scholar Obata Kagenori. Although he has been said to be a fictitious character, his existence was proven with the discovery of the "Ichikawa Documents," and the "Hagi Hanbatsu Etsuroku" (Yamaguchi Prefectural Archives) reveals that Kansuke's descendants served the Mori clan in Yamaguchi.

[Katsumasa Watanabe]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

室町時代の兵法者。晴幸(はるゆき)ともいい、法名は入道道鬼(にゅうどうどうき)。讃岐(さぬき)（香川県）に生まれる。山口へ行き大内義隆(よしたか)に仕えたのち浪人し、武田晴信(はるのぶ)（信玄）に仕官。兵法に優れ、軍師として重用され、軍略、築城、甲州法度(はっと)の草案など、抜群の功績をあげた。1561年（永禄4）9月10日、武田・上杉の川中島合戦において「きつつきの戦法」を提案し、大激戦の結果、壮烈な討ち死にを遂げた。甲州流兵法の祖とされ、徳川の軍学者小幡景憲(おばたかげのり)によって勘介の名は全国的に広まった。架空の人物といわれたこともあるが、「市川文書」発見で実在が証明され、また『萩藩閥閲録(はぎはんばつえつろく)』（山口県文書館）によって、山口で勘介の子孫が毛利に仕えたことが明らかになっている。

［渡辺勝正］

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