Munenori entered the service of
Tokugawa Ieyasu at a young age, and was later an instructor of swordsmanship to Ieyasu's son
Hidetada. He eventually became one of the primary advisors of the third shōgun,
Iemitsu. Shortly before his death in 1606, Sekishusai passed the leadership of Yagyū Shinkage-ryū to his grandson
Toshiyoshi. Following a period of
musha shugyō, Toshiyoshi entered the service of a cadet branch of the Tokugawa clan that controlled the
Owari province. Toshiyoshi's school was based in
Nagoya and came to be called (), while Munenori's, in
Edo, the Tokugawa capital, came to be known as (). Takenaga Hayato, the founder of the
Yagyū Shingan-ryū, was a disciple of Yagyū Munenori and received
gokui (secret teachings) of the Yagyū Shinkage-ryū from him. In about 1632, Munenori completed the
Heihō kadensho (
A Hereditary Book on the Art of War), a treatise on practical Shinkage-ryū swordsmanship and how it could be applied on a macro level to life and politics. The text remains in print in Japan today, and has been translated a number of times into English. Munenori's sons,
Yagyū Jūbē Mitsuyoshi and
Yagyū Munefuyu, were also famous swordsmen. The essay
The Mysterious Record of Immovable Wisdom by
Takuan Sōhō was a letter written from Sōhō to Munenori. ==Bibliography==