So Mitsuhashi grew vegetables and worked on his martial arts techniques, in addition to copious ninja study in the classroom.
“With this combination, I thought I could learn about the real ninja,” he said.
Better known as black-clad assassins famous for secrecy and stealth, ninjas also had “comprehensive survival skills,” he added.
Mitsuhashi, who has also learned kung fu and a Japanese martial art known as Shorinji Kempo, teaches ninja skills at his own dojo and runs a local inn while pursuing his PhD.
The Mie University set up the world’s first research center devoted to the ninja in 2017 and opened a graduate course a year later.
It is located in Iga — 350 kilometers (220 miles) southwest of Tokyo — a mountain-shrouded city once home to many ninja.