Iga-ryu

It is a mainstream school of ninjutsu alongside the Koga school. It is a type of ninja art that was passed down among local samurai and local samurai in Iga (northwestern Mie prefecture), and includes techniques such as lookouts, night attacks, and strong theft. It is a martial art that was developed based on the ancient mountain ascetic military techniques of this region, adding the skill of fire techniques and creating various ninja tools. Perhaps due to its secrecy, there are very few written documents, and unlike general martial arts schools, the founder and lineage are not clear, but it reached a state of near perfection during the Sengoku period, and is commonly known as the 49 Iga schools, with Iga school being the general name for them.

Iga Province is surrounded by rugged mountains on all sides, and the mountainous areas, excluding the Iga Basin, have a complex topography, with little arable land and not much soil. However, historically it was a key transportation location connecting Ise with centers of political power such as Yamato, Yamashiro, and Omi, and from early on, manors for temples and shrines such as Todaiji Temple, Kofuku-ji Temple, and Ise Grand Shrine were established there, and from the mid-Kamakura period through the Nanboku-cho period, local samurai emerged in large numbers in various places, including the Kuroda gang who opposed the rule of Todaiji Temple. Even in the Muromachi period, no unifying power developed, and small factions inevitably split off, competing with each other and constantly needing to investigate trends in neighboring countries. This gave rise to the custom that "it is best to defeat a large force with a small one, and to defeat the strong with the weak, and so all warriors in their daily lives devised ways to be sneaky, and taught their servants how to sneak" (Ninjutsu Mondo, Mansenshukai). The neighboring Koga region (southern Shiga Prefecture) also excelled in the art of stealth due to similar historical and geographical circumstances, but it is said that the Iga and Koga ninja groups first made their presence known in 1487 (Chokyo 1), when Shogun Ashikaga Yoshihisa attacked Rokkaku Takayori of Omi, and performed a remarkable feat at the so-called Magari (Awata County, Omi Province) camp. Famous leaders of the Iga ninja (called jonin) who were active from the end of the Muromachi period to the Sengoku period were Fujibayashi Nagatonokami of northern Iga and Momochi Tamba of southern Iga, as well as the father-son duo Hattori Hanzo Yasunaga and Hanzo Masanari, who served the Matsudaira clan of Mikawa and later the Tokugawa clan. Furthermore, the area produced many masters of stealth, including Igazaki Dojun of Tateoka in Ayama County, Ooi Magodayu of Nomura, Kotaro of Shindo, Kizaru and Kozaru of Shimotsuge, Hidari of Ueno, Yaemon of Yamada, Konan of Kobe, Kido of Ondo, and Taroshiro and Tarozaemon of Takayama.

In 1579 (Tensho 7), Kitabatake Nobukatsu attacked Iga, and in 1581, Oda Nobunaga attacked Iga. The local samurai of Iga united to fight back, and although they repelled Nobukatsu's forces, they were ultimately defeated by Nobunaga's overwhelming military force. Many of the local samurai escaped pursuit and fled to Yamato, Yamashiro, Tamba, and Kawachi, or sought refuge with daimyo such as Tokugawa Ieyasu, Maeda Toshiie, and Fukushima Masanori. In the following year, 1582, after the Honnoji Incident, 200 Iga samurai were employed as police officers for their contributions in helping Ieyasu return to Mikawa from Sakai in Senshu. Under the command of the head of the secret police, Hattori Hanzo Masanari, they played an active role in the Sieges of Nagakute, Sekigahara, and Osaka, and raised the name of the Iga style. Famous Iga-ryu texts include the four-volume "Ninpiden," compiled in 1653 (Shoo 2) by Hattori Mino no Kami Yasukiyo from the traditions passed down from Hattori Hanzo, and the 22-volume "Mansenshukai," compiled in 1676 (Enpo 4) by Fujibayashi Yasutake of Iga Yufune and intended to be a compilation of ninjutsu.

[Ichiro Watanabe]

"Ninjutsu" by Adachi Makiichi (1957, Heibonsha)" ▽ "Ninjutsu Secrets" by Okusae Heishichirou (1959, Heibonsha)" ▽ "Ninjutsu - Its History and Ninjas" by Okusae Heishichirou (1963, Jinbutsu Oraisha)" ▽ "The Life of the Ninja" by Yamaguchi Masayuki (1963, Yuzankaku) ▽ "Complete Collection of Japanese Martial Arts, Volume 4" (1966, Jinbutsu Oraisha) ▽ "The Encyclopedia of Japanese Martial Arts, Volume 5" (1982, Dohosha Publishing)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

甲賀流と並ぶ忍術の主流派。伊賀（三重県北西部）の地侍や郷士の間に伝えられた物見(ものみ)、夜討(ようち)、剛盗(ごうとう)など、いわゆる細作(さいさく)（忍び）の術であり、この地方に古来の山伏兵法をもととして、火術の妙を加え、種々の忍具を創案して編み出された武術をいう。その秘密性からか伝書もきわめて少なく、一般の武術流派のような流祖や伝系が明確ではないが、戦国時代を通じてほぼ完成の域に達したもので、俗に伊賀四十九流といわれ、伊賀流はその総称である。

　伊賀の国は四周を山嶮(さんけん)に囲まれ、伊賀盆地を除く山間部は複雑な地形をなし、耕地も乏しく地味も豊かではないが、歴史的に大和(やまと)、山城(やましろ)、近江(おうみ)などの政治権力の中心と伊勢(いせ)を結ぶ交通の要地にあたり、早くから東大寺、興福寺、伊勢神宮など寺社の荘園(しょうえん)が分置され、鎌倉中期から南北朝にかけては東大寺の支配に対抗する黒田の悪党をはじめ、各地に地侍が群立した。室町時代に入っても、これを統一する権力が育たず、いきおい小党分立して、互いにしのぎを削って抗争し、つねに隣接の動向を探索する必要があり、「小勢を以(もっ)て多勢に勝ち、柔弱を以て剛強に勝つ事、忍(しのび)を入るゝにしくはなしとて、何(いづ)れの士も平生忍の手段を工夫し、隠忍をば下人どもに習はせり」（『萬川集海(まんせんしゅうかい)』忍術問答）という風習が生じた。隣接する甲賀地方（滋賀県南部）も同様な歴史的、地理的環境から忍びの術に長じたが、伊賀、甲賀の忍者集団がその存在を明らかにしたのは、1487年（長享1）将軍足利義尚(あしかがよしひさ)が近江の六角高頼(ろっかくたかより)を攻めた際、いわゆる鈎(まがり)（近江国粟田(あわた)郡）の陣において奇功をたてたのが最初といわれる。室町末期から戦国期に活躍した伊賀忍者の頭領（上忍という）には、北伊賀の藤林長門守(ながとのかみ)と南伊賀の百地丹波(ももちたんば)、および三河の松平氏、後の徳川氏に仕えた服部半三保長(はっとりはんぞうやすなが)・半蔵正成(まさなり)父子などが有名であった。また隠忍の名人として、阿山(あやま)郡楯岡(たておか)の伊賀崎道順(どうじゅん)をはじめ、野村の大炊(おおい)孫太夫、新堂の小太郎、下柘植(しもつげ)の木猿・小猿、上野の左、山田の八右衛門、神戸(かんべ)の小南(こなん)、音戸(おんど)の城戸(きど)、高山(こうやま)の太郎四郎・太郎左衛門などが輩出した。

　やがて1579年（天正7）北畠(きたばたけ)信雄、1581年織田信長の伊賀攻めには、伊賀の地侍は連合してこれに対抗し、信雄の軍は撃退したが信長の圧倒的な軍勢についに敗れ、地侍の多くは追及を逃れて大和、山城、丹波(たんば)、河内(かわち)に流散、また徳川家康や前田利家(としいえ)、福島正則(まさのり)らの大名を頼った。翌1582年本能寺の変後、泉州堺(さかい)にあった家康の三河への帰還に協力した功により、伊賀郷士200人が同心に採用され、隠密頭(おんみつがしら)服部半蔵正成のもとで、長久手、関ヶ原、大坂の陣などで活躍し、伊賀流の名を高めた。なお、伊賀流の伝書としては、服部半蔵からの伝承を1653年（承応2）服部美濃(みの)守保清がまとめた『忍秘伝(にんぴでん)』4冊と、1676年（延宝4）伊賀湯舟の藤林保武(やすたけ)が忍術の集大成を図った『萬川集海』22巻が有名。

［渡邉一郎］

『足立巻一著『忍術』（1957・平凡社）』▽『奥瀬平七郎著『忍術秘伝』（1959・平凡社）』▽『奥瀬平七郎著『忍術――その歴史と忍者』（1963・人物往来社）』▽『山口正之著『忍者の生活』（1963・雄山閣）』▽『『日本武道全集　第4巻』（1966・人物往来社）』▽『『日本武道大系　第5巻』（1982・同朋舎出版）』

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