Editing Ninja (section)

==History==
Despite many popular folktales, historical accounts of the ninja are scarce. The social origin of the ninja is seen as the reason they agree to operate in secret, trading their service for money without honor and glory.<ref name=":1">{{Cite book|title=Mercenaries: A Guide to Private Armies and Private Military Companies|last=Axelrod|first=Alan|publisher=CQ Press|year=2015|isbn=978-1-4833-6467-4|location=Washington, D.C.}}</ref>

However, some ''[[ninjutsu]]'' books described specifically what tactics ninja should use to fight, and the scenarios in which a ninja might find themselves can be deduced from those tactics. For example, in the manuscript of volume 2 of ''Kanrin Seiyō'' (間林清陽) which is the original book of ''Bansenshūkai'' (万川集海), there are 48 points of ninja's fighting techniques, such as how to make ''[[makibishi]]'' from bamboo, how to make footwear that makes no sound, fighting techniques when surrounded by many enemies, precautions when using swords at night, how to listen to small sounds, ''[[kuji-kiri]]'' that prevents guard dogs from barking, and so on.<ref>{{cite web|url=https://www.sankei.com/article/20220619-TZZ42J6D45NENAYKGQLBDLRPNY/|archive-url=https://web.archive.org/web/20220620085044/https://www.sankei.com/article/20220619-TZZ42J6D45NENAYKGQLBDLRPNY/|script-title=ja:甲賀で忍術書の原典発見 番犬に吠えられない呪術も「間林清陽」48カ条|language=ja|publisher=[[Sankei Shimbun]]|date=19 June 2022|archive-date=20 June 2022}}</ref><ref>{{cite web|url=https://www3.nhk.or.jp/kansai-news/20220619/2000062476.html|archive-url=https://web.archive.org/web/20220619102048/https://www3.nhk.or.jp/kansai-news/20220619/2000062476.html|script-title=ja:忍者の里 甲賀市で忍術書の基となった書の写本初めて見つかる|language=ja|publisher=[[NHK]]|date=19 June 2022|archive-date=19 June 2022}}</ref>

===Predecessors===
[[File:Yamato Takeru at 16-crop.jpg|thumb|upright|Yamato Takeru dressed as a maidservant, preparing to kill the Kumaso leaders. Woodblock print on paper. [[Yoshitoshi]], 1886.]]
The title ''ninja'' has sometimes been attributed retrospectively to the semi-legendary 2nd-century prince [[Yamato Takeru]].<ref name="Waterhouse 1996 34">{{Harvnb|Waterhouse|1996|pp=34}}</ref> In the ''[[Kojiki]]'', the young Yamato Takeru disguised himself as a charming maiden and assassinated two chiefs of the [[Kumaso]] people.<ref name="Chamberlain 2005 249-253">{{Harvnb|Chamberlain|2005|pp=249–253}}; Volume 2, section 80</ref> However, these records take place at a very early stage of Japanese history, and they are unlikely to be connected to the ''shinobi'' of later accounts. The first recorded use of espionage was under the employment of [[Prince Shōtoku]] in the 6th century.<ref name="ratti 1991 325">{{Harvnb|Ratti|Westbrook|1991|p=325}}</ref> Such tactics were considered unsavory even in early times, when, according to the 10th-century ''Shōmonki'', the boy spy [[Hasetsukabe no Koharumaru]] was killed for spying against the insurgent [[Taira no Masakado]].<ref name="friday 2007 58 60">{{Harvnb|Friday|2007|pp=58–60}}</ref> Later, the 14th-century war chronicle ''[[Taiheiki]]'' contained many references to ''shinobi''<ref name="Waterhouse 1996 34" /> and credited the destruction of a castle by fire to an unnamed but "highly skilled ''shinobi''".

===Early history===
It was not until the 15th century that spies were specially trained for their purpose. It was around this time that the word ''shinobi'' appeared to define and clearly identify ninja as a secretive group of agents. Evidence for this can be seen in historical documents, which began to refer to stealthy soldiers as ''shinobi'' during the [[Sengoku period]]. Later manuals regarding espionage are often grounded in Chinese [[military strategy]], quoting works such as ''[[The Art of War]]'' by [[Sun Tzu]].<ref name="ratti 1991 324">{{Harvnb|Ratti|Westbrook|1991|p=324}}</ref>

By the Sengoku period, the ''shinobi'' had several roles, including spy (''kanchō''), [[Reconnaissance|scout]] (''teisatsu''), surprise attacker (''kishu''), and agitator (''konran''). The ninja families were organized into larger [[guild]]s, each with their own territories.<ref name="ratti 1991 327">{{Harvnb|Ratti|Westbrook|1991|p=327}}</ref> A system of rank existed. A ''jōnin'' ("upper person") was the highest rank, representing the group and hiring out mercenaries. This is followed by the ''chūnin'' ("middle person"), assistants to the ''jōnin''. At the bottom was the ''genin'' ("lower person"), field agents drawn from the lower class and assigned to carry out actual missions.<ref name="draeger smith 1981 121">{{Harvnb|Draeger|Smith|1981|p=121}}</ref>

===Iga and Kōga clans===
{{Main|Iga ikki|Kōka ikki|Iga–Kōka alliance}}
[[File:ReizanView.JPG|thumb|The plains of [[Iga Province|Iga]], nested in secluded mountains, gave rise to villages specialized in the training of ninja.]]
The Iga and Kōga "clans" were ''jizamurai'' families living in the province of [[Iga Province|Iga]] (modern [[Mie Prefecture]]) and the adjacent region of [[Kōka District, Shiga|Kōka]] (later written as ''Kōga''), named after a village in what is now [[Shiga Prefecture]]. From these regions, villages devoted to the training of ninja first appeared.<ref name="Deal 2007 165">{{Harvnb|Deal|2007|p=165}}</ref> The remoteness and inaccessibility of the surrounding mountains in Iga may have had a role in the ninja's secretive development.<ref name="draeger smith 1981 121" />  The chronicle ''Go Kagami Furoku'' writes, of the two clans' origins:

{{blockquote|There was a retainer of the family of Kawai Aki-no-kami of Iga, of pre-eminent skill in ''shinobi'', and consequently for generations the name of people from Iga became established. Another tradition grew in Kōga.}}

Likewise, a supplement to the ''Nochi Kagami'', a record of the [[Ashikaga shogunate]], confirms the same Iga origin:

{{blockquote|Inside the camp at Magari of the ''[[Shogun|shōgun]]'' <nowiki>[</nowiki>Ashikaga<nowiki>]</nowiki> [[Ashikaga Yoshihisa|Yoshihisa]] there were ''shinobi'' whose names were famous throughout the land. When Yoshihisa attacked [[Rokkaku clan|Rokkaku Takayori]], the family of Kawai Aki-no-kami of Iga, who served him at Magari, earned considerable merit as ''shinobi'' in front of the great army of the ''shōgun''. Since then successive generations of Iga men have been admired. This is the origin of the fame of the men of Iga.}}

These professional ninja were actively hired by ''[[Daimyo|daimyō]]s'' between 1485 and 1581. Specifically, the Iga professionals were sought after for their skill at siege warfare, or "shirotori", which included night attacks and ambush.<ref>{{Cite conference |last=Nakagawa |first=Takaaki |date=2015 |title=Lecture No. 4: "The Samurai Powers in the Kinai (Capital Region) and Iga" – (2nd term) |url=https://www.human.mie-u.ac.jp/en/projects/iga/lecture/2015/2015-10.html |conference=Conference with the Cooperation of Iga on Ninja Culture |publisher=[[Mie University]] |conference-url=https://www.human.mie-u.ac.jp/en/projects/iga/}}; {{Cite conference |last=Kenji |first=Kasai |date=2012 |title=Lecture No.2: Activities of Igashu in the Sengoku Period |url=https://www.human.mie-u.ac.jp/en/projects/iga/lecture/2012/k20121124.html |conference=Conference with the Cooperation of Iga on Ninja Culture |publisher=[[Mie University]] |quote=What we can conclude from the writing is that it was already well-known among people in the end of Sengoku period that sneaking and making night attacks were Ninja's favorite tactics. |conference-url=https://www.human.mie-u.ac.jp/en/projects/iga/lecture/2015/2015-1.html}}</ref> By the 1460s, the leading families in the regions had established ''de facto'' independence from their ''[[shugo]]''. The [[Kōka ikki|Kōka ''ikki'']] persisted until 1574, when it was forced to become a vassal of [[Oda Nobunaga]]. The [[Iga ikki|Iga ''ikki'']] continued until 1581, when Nobunaga invaded Iga Province and wiped out the organized clans.<ref name="Green 2001 357">{{Harvnb|Green|2001|p=357}}</ref> Survivors were forced to flee, some to the mountains of [[Kii Mountains|Kii]], but others arrived before [[Tokugawa Ieyasu]], where they were well treated. Some former Iga clan members, including [[Hattori Hanzō]], would later serve as Tokugawa's bodyguards.<ref name="Adams 1970 43">{{Harvnb|Adams|1970|p=43}}</ref> Prior to the conquest of Kōka in 1574, the two confederacies worked in [[Iga–Kōka alliance|alliance together]] from at least 1487.

Following the [[Battle of Okehazama]] in 1560, Tokugawa employed a group of eighty Kōga ninja, led by Tomo Sukesada. They were tasked to raid an outpost of the [[Imagawa clan]]. The account of this assault is given in the ''Mikawa Go Fudoki'', where it was written that Kōga ninja infiltrated the castle, set fire to its towers, and killed the [[castellan]] along with two hundred of the garrison.

=== Activities under Tokugawa ===
After the assassination of Oda Nobunaga, Iga and Kōka ninja, according to tradition, helped Ieyasu undergo an [[:ja:伊賀越え|arduous journey]] to escape the enemies of Nobunaga in [[Sakai]] and return to [[Mikawa Province|Mikawa]]. However, their journey was very dangerous due to the existence of [[:ja:落ち武者狩り|"Ochimusha-gari"]] groups across the route.{{efn|According to Imatani Akira, professor of [[Tsuru University]], and Ishikawa Tadashi, assistant professor [[University of Central Florida]], during [[Sengoku period]] a particularly dangerous groups called [[:jp:落ち武者狩り|"Ochimusha-gari"]] or "fallen warrior hunter" groups has emerged. these groups were disenfranchised peasant or [[Rōnin]] who has been displaced by war. They formed self-defense forces which operates outside the law, while in actuality they often resorted to hunt samurais or soldiers who has been defeated in wars.<ref name="SAMURAI HUNTER1">{{cite book |author1=Fujiki Hisashi |title=刀狩り: 武器を封印した民衆 |date=2005 |publisher=岩波書店 |isbn=4004309654 |page=29･30 |language=Ja |quote=[[Kunio Yanagita]] “History of Japanese Farmers”}}</ref><ref name="SAMURAIHUNTER2">{{cite book |author1=Kirino Sakuto |title=真説本能寺 (学研M文庫 R き 2-2) |date=2001 |publisher=学研プラス |isbn=4059010421 |pages=218–9 |language=Ja |quote=Tadashi Ishikawa quote}}</ref><ref name="SAMURAIHUNTER3">{{Cite book|author= Akira Imatani |date= 1993 |pages=152–153, 157–158,､167 |quote=Akira Imatani“Practice of attacking fallen warriors”; 2000; p.153 chapter 4 |title=天皇と天下人|publisher=新人物往来社|isbn=4404020732}}</ref>}} During this journey, Tokugawa generals such as [[Ii Naomasa]], [[Sakai Tadatsugu]] and [[Honda Tadakatsu]] fought their way through raids and harassment from Ochimusha-gari (Samurai hunter) outlaws to secure the way for Ieyasu, while sometimes advancing by usage of gold and silver bribes given to some of the more amenable Ochimusha-gari groups.<ref name="SAMURAIHUNTER4">{{cite book |author1=Mitsuhisa Takayanagi |url=https://ndlsearch.ndl.go.jp/books/R100000039-I2973958 |title=戦国戦記本能寺の変・山崎の戦 (1958年) |date=1958 |publisher=春秋社 |page=65 |language=Ja |quote=[[Luís Fróis]];''History of Japan''..; Nihon Yoso-kai Annual Report”, Japanese historical materials also show that Ieyasu distributed a large amount of gold and silver to his subordinates) A certain “ Ishikawa Tadashi Sosho |access-date=9 May 2024}}</ref> As they reached Kada, an area between [[Kameyama, Mie|Kameyama town]] and Iga,<ref name="fujita">{{Cite journal |author=藤田達生 |date=2005 |title=「神君伊賀越え」再考 |url=https://doi.org/10.24707/aichikenshikenkyu.9.0_1 |journal=愛知県史研究 |publisher=愛知県 |volume=9 |pages=1–15|doi=10.24707/aichikenshikenkyu.9.0_1 }}</ref> The attacks from Ochimusha-gari finally ended as they reached the former territory of the Kōka ikki, who were friendly to the Tokugawa clan. The Koka ninja assisted the Tokugawa escort group in eliminating the threats of Ochimusha-gari outlaws then escorting them until they reached [[Iga Province]], where they were further protected by samurai clans from Iga ikki which accompanied the Ieyasu group until they safely reached Mikawa. The ''[[Matsudaira Ietada (Fukōzu)#Legacy|Ietada nikki]]'' journal records that the escort group of Ieyasu has killed some 200 outlaws during their journey from Osaka.<ref name="IetadaNikkiIgacross">{{Cite web |author=Masahiko Iwasawa |date=1968 |title=(Editorial) Regarding the original of Ietada's diary |url=https://www.hi.u-tokyo.ac.jp/publication/syoho/02/syoho0002-iwazawa.pdf |accessdate=2022-11-16 |website=東京大学史料編纂所報第２号}}</ref><ref>{{Cite book |author=Morimoto Masahiro |url=https://bookmeter.com/books/20204283 |title=家康家臣の戦と日常 松平家忠日記をよむ (角川ソフィア文庫) Kindle Edition |date=1999 |publisher=KADOKAWA |access-date=10 May 2024}}</ref>

The Kōga ninja are said to have played a role in the later [[Battle of Sekigahara]] (1600), where several hundred Kōga assisted soldiers under [[Torii Mototada]] in the defence of [[Fushimi Castle]]. After Tokugawa's victory at Sekigahara, the Iga acted as guards for the inner compounds of [[Edo Castle]], while the Kōga acted as a police force and assisted in guarding the outer gate.<ref name="Adams 1970 43" /> In 1603, a group of ninja warriors from Iga clan led by Miura Yo'emon were assigned under the command of [[Ii Naomasa#Ii clan's Red Demons brigade|Red Demon brigades]] of Ii Naomasa, the daimyo of [[Hikone, Shiga|Hikone]] under Tokugawa shogunate.

In 1608, a daimyo named [[Tōdō Takatora]] was assigned by Ieyasu to control of [[Tsu Domain|Tsu]], a newly established domain which covered portions of Iga and [[Ise Province]]. The domain at first worth of to the 220,000,{{sfn|Nakayama|2015}} then grow further in productivity to the total revenue of 320,000 koku under Takatora governance.<ref>{{cite book |author1=Yuji Yamada |url=https://books.google.com/books?id=2FwUDgAAQBAJ |title=THE NINJA BOOK: The New Mansenshukai |date=2017 |publisher=Mie University Facultyof Humanities, Law and Economics |language=En |translator=Atsuko Oda |access-date=11 May 2024}}</ref><ref name="Gaku">{{cite book |last1=Oishi |first1=Gaku |title=江戸五百藩-ご当地藩のすべてがわかる |date=2020 |publisher=Chuokoron-Shinsha |isbn=978-4128001354}}{{in lang|ja}}</ref> It was reported that Tōdō Takatora employs the [[Iga-ryū]] Ninjas. Aside from Ninjas, he also employs local clans of Iga province as "Musokunin", which is a class of part time Samurai who has been allowed to retain their clan name but does not own any land or ''[[Han system|Han]]''. The Musokunin also worked as farmer during peace, while they are obliged to take arms in the time of war.<ref name="Kenji Fukui 2018 165">{{harvtxt|Kenji Fukui|2018|p=165}}</ref><ref name="Iga Musokunin; Todo Takatora">{{cite book |url=https://www.rekishikaido.gr.jp/catv/2018/906/ |title=254: 藤堂藩を裏で支えた無足人 |publisher=Rekishi Kaido Promotional Council |language=Ja |access-date=11 May 2024}}</ref><ref name="Count Todo; 695">{{harvtxt|Iwata Nishizawa|1917|p=695}}</ref>

In 1614, The Iga province warriors saw action during the [[siege of Osaka]]. Takatora brought the Musokunin auxiliaries from Iga province to besiege the Osaka castle during the winter phase.<ref name="Kenji Fukui 2018 165"/><ref name="Iga Musokunin; Todo Takatora" /> Meanwhile the ninja units of Iga province were deployed under several commanders such as [[Hattori Hanzō]], and Yamaoka Kagetsuge, and [[Ii Naotora]], heir of Naomasa who also given control of Ii clan's Red Demons ninjas after Naomasa died. Later in 1615, during the summer phase of Osaka siege, The Ii clan Red Demons ninjas led by Miura Yo'emon, Shimotani Sanzo, Okuda Kasa'emon, and Saga Kita'emon saw action once again during the [[Battle of Tennōji]], as they were reportedly fought together with the Tokugawa regular army storming on the south gate of Osaka castle. In 1614, the initial "winter campaign" at the [[Siege of Osaka]] saw the ninja in use once again. Miura Yoemon, a ninja in Tokugawa's service, recruited ''shinobi'' from the Iga region, and sent 10 ninja into [[Osaka Castle]] in an effort to foster antagonism between enemy commanders.During the later "summer campaign", these hired ninja fought alongside regular troops at the [[Battle of Tennōji]].

===Shimabara rebellion===
[[File:Ninja Historic Illustration 18th Century.png|thumb|Ninja historic illustration, Meiwa era, {{Circa|1770}}]]

A final but detailed record of ninja employed in open warfare occurred during the [[Shimabara Rebellion]] (1637–1638). The Kōga ninja were recruited by ''[[Shogun|shōgun]]'' [[Tokugawa Iemitsu]] against [[Christianity in Japan|Christian]] rebels led by [[Amakusa Shirō]], who made a final stand at [[Hara Castle]], in [[Hizen Province]]. A diary kept by a member of the [[Matsudaira clan]], the ''Amakusa Gunki'', relates: "Men from Kōga in [[Ōmi Province]] who concealed their appearance would steal up to the castle every night and go inside as they pleased."

The Ukai diary, written by a descendant of Ukai Kanemon, has several entries describing the reconnaissance actions taken by the Kōga.

{{blockquote|They [the Kōga] were ordered to reconnoitre the plan of construction of Hara Castle, and surveyed the distance from the defensive [[moat]] to the ''ni-no-maru'' (second [[Motte-and-bailey castle|bailey]]), the depth of the moat, the conditions of roads, the height of the wall, and the shape of the loopholes.<ref name="Turnbull 2003 51">{{Harvnb|Turnbull|2003|p=51}}</ref>|Entry: 6th day of the 1st month}}

[[File:Remains of Hara castle.jpg|thumb|The ruins of [[Hara Castle]]]]
Suspecting that the castle's supplies might be running low, the siege commander [[Matsudaira Nobutsuna]] ordered a raid on the castle's provisions. Here, the Kōga captured bags of enemy provisions, and infiltrated the castle by night, obtaining secret passwords. Days later, Nobutsuna ordered an intelligence gathering mission to determine the castle's supplies. Several Kōga ninja—some apparently descended from those involved in the 1562 assault on an [[Imagawa clan]] castle—volunteered despite being warned that chances of survival were slim. A volley of shots was fired into the sky, causing the defenders to extinguish the castle lights in preparation. Under the cloak of darkness, ninja disguised as defenders infiltrated the castle, capturing a banner of the [[Christian cross]]. The Ukai diary writes,

{{blockquote|We dispersed spies who were prepared to die inside Hara castle.&nbsp;... those who went on the reconnaissance in force captured an enemy flag; both Arakawa Shichirobei and Mochizuki Yo'emon met extreme resistance and suffered from their serious wounds for 40 days.|Entry: 27th day of the 1st month}}

As the siege went on, the extreme shortage of food later reduced the defenders to eating [[moss]] and grass. This desperation would mount to futile charges by the rebels, where they were eventually defeated by the shogunate army. The Kōga would later take part in conquering the castle:

{{blockquote|More and more general raids were begun, the Kōga ninja band under the direct control of Matsudaira Nobutsuna captured the ''ni-no-maru'' and the ''san-no-maru'' (outer bailey)|Entry: 24th day of the 2nd month}}

With the fall of Hara Castle, the Shimabara Rebellion came to an end, and Christianity in Japan was forced [[Kakure Kirishitan|underground]].<ref name="Morton Olenik 2004 122">{{Harvnb|Morton|Olenik|2004|p=122}}</ref> These written accounts are the last mention of ninja in war.<ref name="Crowdy 2006 52">{{Harvnb|Crowdy|2006|p=52}}</ref>

===Edo period===
After the Shimabara Rebellion, there were almost no major wars or battles until the ''[[bakumatsu]]'' era. To earn a living, ninja had to be employed by the governments of their ''[[Han system|Han]]'' (domain), or change their profession. Many lords still hired ninja, not for battle but as bodyguards or spies. Their duties included spying on other domains, guarding the daimyō, and fire patrol.<ref>{{Harvnb|Yamada|2019|pp=176–177}}</ref> A few domains like [[Tsu Domain|Tsu]], [[Hirosaki Domain|Hirosaki]] and [[Saga Domain|Saga]] continued to employ their own ninja into the ''bakumatsu'' era, although their precise numbers are unknown.<ref>{{Harvnb|Yamada|2019|pp=188–189}}</ref><ref name=Benkei/>

Many former ninja were employed as security guards by the [[Tokugawa shogunate]], though the role of espionage was transferred to newly created organizations like the ''onmitsu'' and the ''[[oniwaban]]''.<ref>{{Harvnb|Yamada|2019|pp=174–175}}</ref> Others used their ''ninjutsu'' knowledge to become doctors, medicine sellers, merchants, martial artists, and fireworks manufacturers.<ref>{{Harvnb|Yamada|2019|pp=178–179}}</ref> Some unemployed ninja were reduced to banditry, such as [[Fūma Kotarō]] and [[Ishikawa Goemon]].<ref>{{Harvnb|Yamada|2019|p=180}}</ref>

{| class="wikitable sortable"
|-
| colspan="2" | '''Ninja employed in each domain, Edo period'''<ref>{{Harvnb|Yamada|2019|p=176}}</ref>
|-
! ''[[Han system|Han]]'' (domain)
! Number of ninja
|-
|[[Kishū Domain]]
|200+
|-
|[[Kishiwada Domain]]
|50
|-
|[[Kawagoe Domain]]
|50
|-
|[[Matsue Domain]]
|30
|-
|[[Hirosaki Domain]]
|20
|-
|[[Fukui Domain]]
|12
|-
|[[Hikone Domain]]
|10
|-
|[[Okayama Domain]]
|10
|-
|[[Akō Domain]]
|5
|}

====Ninja stereotypes in theatre====
{{multiple image
| total_width=350
| image1 = 005-1134.jpg
| alt1 =
| caption1 = In ''Sakura doki onna gyoretsu'', this [[Onnagata|{{Transliteration|ja|onnagata}}]] is attended by three {{Transliteration|ja|kuroko}}.
| image2 = Ninja-and-Prince-Genji-Ukiyoe-Utagawa-Kunisada.png
| alt2 =
| caption2 = In ''[[Nise Murasaki Inaka Genji]]'', Ashikaga Mitsuuji is approached unknowingly by a ninja.
| footer = Two prints depicting [[kabuki]] plays. In Japanese theatre, ninja are often dressed as [[Kuroko|{{Transliteration|ja|kuroko}}]], stagehands in black suits, to make their attacks seem more surprising. This practice gave rise to their stereotypical black outfits.<ref name=Kamm />}}
Many ubiquitous stereotypes about ninja were developed within Edo theatre. These include their black clothing, which was supposed to imitate the outfits worn by [[Kuroko|{{Transliteration|ja|kuroko}}]], stagehands meant to be ignored by the audience; and their use of [[Shuriken|{{Transliteration|ja|shuriken}}]], which was meant to contrast with the use of swords by onstage samurai. In [[kabuki]] theatre, ninja were "dishonorable and often sorcerous counterparts" to samurai, and possessed "almost, if not outright, magical means of camouflage."<ref name=Kamm>{{cite journal|author-last=Kamm|author-first=Björn-Ole|title=Reenacting Japan's Past That Never Was: The Ninja in Tourism and Larp|journal=Reenactment Case Studies: Global Perspectives on Experiential History|pages=146–170|date=2022|access-date=7 March 2023|url=https://books.google.com/books?id=iMKZEAAAQBAJ&dq=info:hYmMz5CJDXsJ:scholar.google.com/&pg=PT174|doi=10.4324/9780429445668-10}}</ref>

===Contemporary===
[[File:Kanrinseiyo_Middle_Volume_Ninja_Manual_1748.png|thumb|upright=1.5|A copy of the legendary 40-page book called ''Kanrinseiyo'' made in 1748]]

Between 1960 and 2010 artifacts dating to the [[Siege of Odawara (1590)]] were uncovered which experts say are ninja weapons.<ref name="livescience"/> Ninja were spies and saboteurs and likely participated in the siege.<ref name="livescience"/> The [[Hojo clan]] failed to save the castle from [[Toyotomi Hideyoshi]] forces.<ref name="livescience"/> The uncovered flat throwing stones are likely predecessors of the [[shuriken]].<ref name="livescience"/> The clay caltrops preceded [[makibishi]] caltrops.<ref name="livescience">{{cite web |title=430-year-old ninja weapons possibly identified |date=February 14, 2022 |author=Owen Jarus |website=Live Science |url=https://www.livescience.com/ancient-ninja-weapons-discovered |archive-url=https://web.archive.org/web/20220311011334/https://www.livescience.com/ancient-ninja-weapons-discovered |archive-date=March 11, 2022}}</ref> Archeologist Iwata Akihiro of [[Saitama Prefectural Museum of History and Folklore]] said the flat throwing stones "were used to stop the movement of the enemy who was going to attack [a soldier] at any moment, and while the enemy freezed the soldier escaped,".<ref name="livescience"/> The clay caltrops could "stop the movement of the enemy who invaded the castle," These weapons were hastily constructed yet effective and used by a "battle group which can move into action as ninjas".<ref name="livescience"/>

[[Mie University]] founded the world's first research centre devoted to the ninja in 2017. A graduate master course opened in 2018. It is located in [[Iga, Mie|Iga]] (now [[Mie Prefecture]]). There are approximately 3 student enrollments per year. Students must pass an admission test about Japanese history and be able to read historical ninja documents.<ref name="Mie-University-Ninja">{{Cite web |date=2020-06-26 |title=Japan university awards first-ever ninja studies degree |url=https://www.france24.com/en/20200626-japan-university-awards-first-ever-ninja-studies-degree |access-date=2025-05-03 |website=France 24}}</ref> Scientific researchers and scholars of different disciplines study ancient documents and how it can be used in the modern world.<ref name="Telangana">{{cite web |title=Japan university to set up ninja research facilities |url=https://telanganatoday.com/japan-university-ninja-research-facilities |access-date=26 June 2020|date=11 May 2017 |publisher= Telangana Today |archive-url=https://web.archive.org/web/20200626191748/https://telanganatoday.com/japan-university-ninja-research-facilities |archive-date=26 June 2020|url-status=live|df=dmy-all}}</ref>

On June 19, 2022, [[Kōka, Shiga|Kōka]] city in [[Shiga Prefecture]] announced that a written copy of "Kanrinseiyo", which is the original source of a famous book on the art of ninja called "Bansenshukai" (1676) from the Edo period was discovered in a warehouse of Kazuraki Shrine.<ref name="kanrinseiyo"/> The handwritten reproduction was produced in 1748.<ref name="sora1">{{cite web |title=First copy of centuries-old ninja training manual discovered, doesn't understand dogs |website=Soranews 24 |author=Casey Baseel |url=https://soranews24.com/2022/06/26/first-copy-of-centuries-old-ninja-training-manual-discovered-doesnt-understand-dogs%E3%80%90video%E3%80%91/ |date=June 27, 2022 |archive-url=https://web.archive.org/web/20220628203338/https://soranews24.com/2022/06/26/first-copy-of-centuries-old-ninja-training-manual-discovered-doesnt-understand-dogs%E3%80%90video%E3%80%91/ |archive-date=June 28, 2022}}</ref> The book describes 48 types of ninjutsu.<ref name="kanrinseiyo"/> It has information about specific methods such as attaching layers of cotton to the bottom of straw sandals to prevent noise when sneaking around, attacking to the right when surrounded by a large number of enemies, throwing charred owl and turtle powder when trying to hide, and casting spells.<ref name="kanrinseiyo"/> It also clarified methods and how to manufacture and use ninjutsu tools, such as cane swords and "makibishi" (Japanese caltrop).<ref name="kanrinseiyo">{{cite news |newspaper=Mainichi Daily News |date=June 21, 2022 |title=Copy of legendary book on art of ninja found at shrine in west Japan city |url=https://mainichi.jp/english/articles/20220621/p2a/00m/0na/025000c |archive-url=https://web.archive.org/web/20220621091201/https://mainichi.jp/english/articles/20220621/p2a/00m/0na/025000c | archive-date=June 21, 2022}}</ref>