The representative ninja of the Sengoku period: How did the Iga and Koga ninjas come into being and disappear?

[From the editorial department] What kind of existence were ninjas? As they were expected to carry out covert operations in the first place, there are few solid historical documents and they have been considered a mysterious group. Nevertheless, they are very popular and proper research has been carried out, and in recent times they are no longer a completely comic book-like entity. This article was contributed to our website from the book "Appr…