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c. Eiroku period (1558–1570)
Various provinces (including Yamato Province, Yagyū)
Forces
Kamiizumi Nobutsuna (founder)
Successor and major disciples
About 11 min read
Shinkage-ryū is a school of swordsmanship founded in the Sengoku period by Kamiizumi Ise-no-kami Nobutsuna, and it exerted a great influence on later Japanese swordsmanship and kendō. Its technical innovation (the invention of the fukuro shinai) and its ideological innovation (the philosophy of katsujinken, the life-giving sword) played a decisive role in transforming swordsmanship in early-modern Japan from a mere combat technique into a path of spiritual cultivation.
Kamiizumi Nobutsuna is said to have been born around Eishō 5 (1508) in Kamiizumi village, Seta District, Kōzuke Province (present-day Maebashi City, Gunma Prefecture), into the Ōgo clan family. From a young age he set his sights on swordsmanship, and after studying various schools including Nen-ryū and Katori Shintō-ryū, he inherited the inner teachings from the lineage of Aisu Ikōsai, the teacher of Kage-ryū. It is said that he added his own innovations to Kage-ryū, developing it into Shinkage-ryū.
During the Tenbun era (1532–1555), he served the two generations of Nagano Narimasa and Narimori, and as a warrior with rich combat experience he also distinguished himself in battle, including in the conflict with Takeda Shingen (until the fall of Nagano Narimori in Eiroku 9 (1566)). After the fall of the Nagano family, Takeda Shingen asked him to enter his service, but he declined and chose the path of swordsmanship training, beginning to travel through the provinces.
Around Eiroku 7 (1564), Nobutsuna gave a demonstration of swordsmanship before the 13th shogun, Ashikaga Yoshiteru. Yoshiteru was himself a shogun known as a master of swordsmanship. It is said that he awarded a certificate of commendation to Marume Nagayoshi, a disciple who served as the uchidachi (attacking swordsman), together with Nobutsuna. The certificate is preserved by the Marume family. In Genki 1 (1570), he is also said to have performed a demonstration before Emperor Ōgimachi.
His activities around this time are recorded 32 times in the diary of Yamashina Tokitsugu, the Tokitsugu-kyō ki, between the 15th day of the 1st month of Eiroku 12 (1569) and the 21st day of the 7th month of Genki 2 (1571), which allows his activities at the time to be corroborated by documentary sources.
The most important of Shinkage-ryū's technical innovations is the devising of the fukuro shinai. The fukuro shinai is a training implement in which split bamboo is placed inside a leather bag, and it is considered the prototype of the modern shinai. Before Nobutsuna, sword training mainly used bokutō (wooden swords), and training close to actual combat carried a great risk of injury and was difficult to carry out except for senior disciples.
The introduction of the fukuro shinai made it possible to greatly reduce injuries during training while still training under conditions close to actual combat. This fundamentally transformed the system of swordsmanship training and made the transmission of techniques to disciples safer and more efficient. The direct origin of modern kendō's shinai training lies here.
The most important ideological renewal that Nobutsuna brought to Shinkage-ryū is the systematization of the concept of katsujinken (the life-giving sword). Many swordsmanship traditions before this were centered on setsunintō (the death-dealing sword), that is, on reliably killing or injuring the opponent. In contrast, Nobutsuna taught that the original purpose of swordsmanship is to subdue an opponent without injuring them, or to prevent conflict before it occurs.
The philosophy of katsujinken extended beyond a mere technical advantage (a skilled technique allows one to subdue an opponent without killing) to the spiritual state of the samurai and to the way of being human. The fact that Yagyū Munenori (a son of Sekishūsai) later developed a similar idea in the Heihō Kadensho, which sets out the essentials of the martial arts, was a succession of the spirit inherited from Nobutsuna through Sekishūsai.
One of the most important encounters in Nobutsuna's journeys through the provinces was with Yagyū Muneyoshi (also known as Sekishūsai, 1527–1606). In Eiroku 6 (1563), on the way to Kyoto, Nobutsuna's party stopped at Nara, and a match was held between them and Muneyoshi, who was defeated. (The opponent is also said to have been Nobutsuna himself, or his disciples Suzuki Ihaku and Hikita Kagetomo.) Defeated, Muneyoshi on the spot asked Nobutsuna to take him as a disciple. He invited Nobutsuna to the Yagyū estate and studied under him, and in Eiroku 8 (1565) he was given an inka-jō (certificate of full transmission).
This certificate is said to be an ikkoku ichinin (one per province) certificate. This is the origin of the school later known as Yagyū Shinkage-ryū. (The formal name of the school remains simply Shinkage-ryū, and “Yagyū Shinkage-ryū” is a colloquial name.) The Yagyū family subsequently became martial arts instructors to the shogunal household across three generations (Tokugawa Ieyasu, Hidetada and Iemitsu), and Shinkage-ryū attained the highest position as the “official swordsmanship” of the Edo shogunate.
Nobutsuna's Shinkage-ryū gave rise to many branch schools, including Hikita Kage-ryū through his direct disciple Hikita Kagetomo, and Taisha-ryū through Marume Nagayoshi. Above all, through the spread of fukuro shinai training and the philosophy of katsujinken, Japanese swordsmanship came after the Edo period to be elevated into something with the spiritual and philosophical depth of a martial way (budō).
Nobutsuna's year of death is given variously as Tenshō 5 (1577) or Tenshō 10 (1582), and it has not been determined. His intellectual legacy, however, has continued to live on through the Edo period into the spirit of modern kendō.