stylistic:style_transfer
Modern era historical evaluations

Between 1960 and 2010 artifacts dating to the Siege of Odawara (1590) were uncovered which experts say are ninja weapons. Ninja were spies and saboteurs and likely participated in the siege. The Hojo clan failed to save the castle from Toyotomi Hideyoshi forces. The uncovered flat throwing stones are likely predecessors of the shuriken. The clay caltrops preceded makibishi caltrops. Archeologist Iwata Akihiro of Saitama Prefectural Museum of History and Folklore said the flat throwing stones were used to prevent the chasing enemies from moving. The clay caltrops also believed could stop the besieging enemies. These weapons were hastily constructed yet effective and used by a squad of ninja.

In 2015 report, a "Ninja Symposium" held in Iga City which involved forefront researchers of ninja and ninjutsu history, including Atsumi Nakajima, chairman of the Koryu Martial Arts Association; Jinichi Kawakami, the 21st head of the Koga Party and a professor of social cooperation at Mie University; Professor Yuji Yamada and Associate Professor Yuya Yoshimaru of the Faculty of Humanities of Mie university; and Toshitsune Watanabe, former chairman of the Koga Ninjutsu Research Association. The symposium discussed about the allegedy rivalry about the two most famous ninja groups based in Iga and Kōka. It was though that the reason of perceived rivalries between them due to the Iga ninja mostly known for their service to the Tokugawa clan, while the Kōka due to their service to the Toyotomi clan. The battles between two groups has been fictionalized and dramatized by modern media and entertainments, such as Yamada Futaro's novel "Koga Ninpocho," published in 1959. Ikeda Yutaka, a senior ninja at the Iga Ninja Research Group, who organized the symposium, said that the Iga and Koga ninja were actually allied and sometimes started uprisings. He further added that there were also many marriages between the two groups, and the Hattori family name, which represents Iga, is also found in many Koga families.

In 2016, on December Iga city Mayor Sakae Okamoto, who is also a collector of local materials, discovered a catalog sent to him by a used bookstore in Kyoto. It was purchased with city funds, and designated a city cultural property in March of this year. This is a written pledge made when 10 representatives each from the Iga Sokoku Ikki and Koka Gunchuso, autonomous organizations of the Iga and Koka clans which gathered together to jointly adjudicate on the right to use the common land.

In 2012, Jinichi Kawakami, the last authentic heir of ninjutsu, decided against passing on his teaching to any student, stating that the art of ninjutsu has no place in modern times. Instead, Kawakami serves as the honorary director of the Iga-ryu Ninja Museum and researches ninjutsu as a specially appointed professor at Mie University.

in 2017, Mie University founded the world's first research centre devoted to the ninja. A graduate master course opened in 2018. It is located in 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. Scientific researchers and scholars of different disciplines study ancient documents and how it can be used in the modern world. Another medieval document that Mie professor Tatsuo Fujita is paying attention to is the "Koka-gun Magistrate-General and Iga Magistrate-General Rensho Kishomon" from 1573 (the first year of the Tensho era).

In 2020, the 45-year-old Genichi Mitsuhashi was the first student to graduate from the master course of ninja studies at Mie University. For 2 years he studied historical records and the traditions of the martial art. Similar to the original ninja, by day he was a farmer and grew vegetables while he did ninja studies and trained martial arts in the afternoon.

In 2022, on June, Kōka city in Shiga Prefecture released the copy of "Kanrinseiyo", the source of a ninjitsu art record called "Bansenshukai" from 1676 which was found Kazuraki Shrine warehouse. The copy was produced in 1748. The book describes 48 types of ninjutsu. It contains information about some ninjitsu techniques such as attaching layers of cotton to the bottom of straw sandals to prevent noise when sneaking, self defense when surrounded by multiple opponents, throwing charred powder to hide one's presence, and spellcastings. It also contain practical methods to manufacture and use tools such as cane swords and "makibishi" (Japanese caltrop).