Watanabe Koan (渡辺幸庵)
Koan WATANABE (1582 - 1711) was a former vassal of Tadanaga TOKUGAWA. His personal name was Shigeru, common name was Kyuzaburo, and pseudonym was Koan. Trained at the Shinkage-ryu school, he was an expert at swordplay.
He was from the Settsu province. He served the Tokugawa family from his youth and attended at the court of Suruga province. In the Battle of Sekigahara, he served as the head clerk of Hidetada TOKUGAWA. Later, he served as a guard of the Fushimi-jo Castle in 1613, a guard of the Sunpu-jo Castle in 1618, and a guard of the Nijo-jo Castle in 1625. During the reign of Hidetada TOKUGAWA, he was chosen as fuyaku (a warrior who educates the Lord's son to become a great leader) of Tadanaga, but after Tadanaga's lands were forfeited and Tadanaga himself was ordered to commit suicide by disembowelment, he underwent hardship of being a ronin (a masterless samurai). He called himself Koan and took a pilgrimage to various districts.
In later years, he stayed with Tsunanori MAEDA and ordered a feudal retainer of the Kaga domain to organize the experiences of his journey into a book called "Conversation with Koan WATANABE". The book also describes about Munenori YAGYU and Musashi MIYAMOTO (the latter is written as Musashi TAKEMURA, who was confused with Yoemon TAKEMURA, a high-caliber disciple) and evaluates Musashi's ability as being higher than that of 'Tajima even in nine-stone handicap Igo (board game of capturing territory) matches'.
He died at an advanced age of 130 in 1711. The age of 130 is not realistic, and a theory exists that he is fictitious from the beginning.
Ryotaro SHIBA created a short story called 'The true story of Musashi MIYAMOTO' based on the description of "Conversation with Koan WATANABE".