There’s hope for the 500-year old practice. Last year, Mie University in Japan’s west coast opened the world’s first academic program on the study of ninja culture. Courses include ancient body control methods, castle architecture, and ninja no shokumotsu—the clean diet of these lean warriors designed to improve mental focus and fortify the body to fight injuries and fatigue.

Though the mode of warfare has changed, ninja arts professor Yuji Yamada explains there are facets of ninja’s spiritual training that’s very relevant today. At the program’s inauguration ceremony, Yamada said, “ninja wisdom tells us a lot about how to coexist with nature at a time when we are surrounded by machines and the artificial materials of the modern age.”

📬 Sign up for the Daily Brief

Our free, fast, and fun briefing on the global economy, delivered every weekday morning.