Skip to contentThe Asahi Shimbun>National Report>By NATSUNO OTAHARA/ Staff WriterSHUNAN, Yamaguchi Prefecture—High school students here have figured out the mechanisms of a medieval eavesdropping device that was among the most important tools for ninja on espionage missions. ” A test on how a “saoto-kikigane” dangled in the air changes sound waves emitted from a speaker (Natsuno Otahara) Three Tokuyama Senior High School science club members with a soft spot for ninja began studying the matter in spring 2021 after checking out Nakashima’s book at their school. ”Nakashima, a long-time student of ninja and ninjutsu, serves as president of an International Ninja Research Association