Yagyū Sekishūsai Taira-no-Munetoshi (柳生石舟斎平宗厳 1529 – May 25, 1606) was a samurai in Japan's Sengoku period famous for mastering the Shinkage-ryū school of combat, and introducing it to the Tokugawa clan.
When Munetoshi was 12, Ietoshi joined a general named Kisawa Nagamasa in contesting the growing power of the warlord Miyoshi Chōkei.
[2] According to the Tamon-in Nikki, a chronicle of the Kōfuku-ji temple, at first the Yagyū were caught by surprise, but Ietoshi rallied his troops for a defensive battle.
[1] Munetoshi soon gained notice as an able warrior and commander, and as many of orders were sent by Tsutsui to him, a young man in his 20s, as were sent to his father, still an active lord in his 50s.
An Owari Yagyū family record suggests that he studied Shintō-ryū under a man named Kantori Shinjūrō.
[5] All family records and Munetoshi's own surviving writings suggest that he was an enthusiastic student of the military arts from a young age, before he met Kamiizumi Hidetsuna.
While stopping in Ise Province, the group asked the governor, Kitabatake Tomonori, if he knew of any capable samurai nearby interested in a friendly match.
[4] Accounts differ on the specifics of the match: according to the Edo Yagyū family record Kyū Yagyū-hanki, Munetoshi faced Hikita Bungoro and was roundly beaten with a fukuro-shinai.
[4] Based on family documents and oral history, Yagyū Toshinaga suggested that Munetoshi's opponent was Hidetsuna himself in three matches over three days.
Hidetsuna, pleased by this innovation, gave Munetoshi an inka-jō, signifying the highest attainment in Shinkage-ryū and permission to teach it.
In 1568, Oda Nobunaga entered Yamato Province with overwhelming force and subjugated the Matsunaga and Tsutsui, ending their skirmishing.
With the passing of a few years, however, Yoshiaki began forming alliances to overthrow Nobunaga, among them the Yagyū's old lord and present commander Matsunaga Hisahide and the warlord Takeda Shingen.
In 1571, attempting to secure control once more over Yamato Province, Matsunaga sent the Yagyū in an attack against Tsutsui Junkei at Tatsuichi, a town in Nara.
Sometime in the late 1570s, Munetoshi gave up all aspirations of being a general or warlord, and retired to Yagyū Village, where he devoted himself to teaching and training in Shinkage-ryū.
Poetry that Munetoshi wrote during this time express doubt and a lack of confidence in anything beyond Shinkage-ryū, and even this skill is compared in utility to a "stone boat".
This same year, he wrote the Heihō Hyakka (兵法百歌, "One-hundred Songs of Strategy"), a collection of mostly original poetry on such subjects as the usefulness, training, and goals of the martial arts.
Despite his seclusion in Yagyū Village, Munetoshi's prowess in Shinkage-ryū and Mutō-dori was known by Tokugawa Ieyasu, at that time still Toyotomi Hideyoshi’s loyal general.
That same year, a census of the Yamato Province revealed hidden, non-taxed rice fields in Yagyū Village.
[3][6] Munetoshi continued to teach Shinkage-ryū, in particular to his grandson Hyōgonosuke Toshitoshi, and Takeda Ujikatsu, the head of the Konparu-ryū school of Noh theater.
[3] The Yagyū family suffered a major loss in 1597, when Munetoshi's oldest grandson and ostensible heir, Sumitoshi, was killed in battle in Korea.
In 1600, the armies of Ishida Mitsunari and Tokugawa Ieyasu began moving against each other to determine who would rule after the death of Toyotomi Hideyoshi.
Ieyasu was attempting to put down an uprising by the Uesugi clan in Shimotsuke Province (present-day Tochigi Prefecture) when he learned that Mitsunari was moving against him.
He dispatched Munenori back to Yagyū Village, to ask his father to raise forces in the Yamato region.
When Toshitoshi returned, Munetoshi, now in ill health, bequeathed to his grandson all of his Shinkage-ryū materials, including the license of transmission and illustrated scrolls he received from Hidetsuna.
After his death, his son Munenori took possession of the family lands in Yagyū Village, and ordered that Hōtokuji Temple be built in Munetoshi's honor.
Munetoshi's oldest son, Toshikatsu, remained in Yagyū Village until his death, his disability preventing him from being employed by a lord.
Toshitoshi's line, the Owari Yagyū, continued to teach and pass down Shinkage-ryū throughout the Edo period, to the present day.
The only suggestion for pronunciation in Yagyū family records was Songon, the Chinese-reading of the characters, which Munetoshi took upon taking the name “Sekishūsai”.
[3] In the Daikanwa Jiten, the largest Chinese character dictionary for the Japanese language, 厳 is given kane, tsuyo, and yoshi as possible readings used in names.
[9] In the video game, Nioh, he appears there as a side quest boss for unlocking the Sword Mystic Art skills.