Katsutoshi Takegami, a retired cafe owner in the city of Komagane, Nagano Prefecture, was cleaning the storehouse of his home seven years ago when he stumbled across a big wooden box.

When he opened it, he found a trove of documents, diaries and photo albums kept by his late father, Toshiichi Miyashita, who spent nearly 15 years as a nurse soldier for the Imperial Japanese Army before and during World War II.

“My father didn’t look like someone who had spent a long time in the military,” Takegami, 77, recalled. “I was never slapped or beaten, and he remained calm even when he had drinks. He never once raised his voice.”