TOKYO, May 29 (Xinhua) -- "Whether my father was involved or not, it (the implementation of germ warfare and human experiments by the Japanese army during its invasion) was inhuman," 77-year-old Katsutoshi Takegami told Xinhua in a recent interview at his home in Komagane City in central Japan's Nagano Prefecture.

Takegami's father, Toshiichi Miyashita, was a member of Unit 1644 of the Imperial Japanese Army during World War II. The unit, established in East China's Nanjing, claimed to be "the Central China Epidemic Prevention and Water Purification Department."

About seven or eight years ago, Takegami discovered several photographs and documents left by his father while renovating his family's warehouse. In the photos, Miyashita was dressed in military uniform, and the name of "the Central China Epidemic Prevention and Water Purification Department" appeared too.

Takegami had learned from "The Devil's Gluttony" by renowned Japanese writer Seiichi Morimura that the epidemic prevention and water purification departments were ostensibly engaged in providing clean water to soldiers but were actually involved in bacteriological warfare and human experiments.

In order to find out whether his father had been involved in germ warfare, Takegami began to investigate, hoping to uncover his father's experiences in China and obtain more historical truths.

However, in Takegami's memory, his father hardly mentioned his experiences in China during his lifetime.

What exactly did Miyashita do in the military? How did he rise from a private to a lieutenant without any education? All these questions troubled Takegami.

Takegami, who took his mother's surname, said "I couldn't find any information about the Central China Epidemic Prevention and Water Supply Department. I didn't even know where to look."

Wartime bacteriological units were secret units of the Japanese army, which destroyed a large amount of documentation when it was defeated. Therefore, the information about the epidemic prevention and water purification departments is particularly scarce.

In fact, there is still information about Unit 1644. The unit's personnel roster, an archival document that details the unit's members, has been secretly kept by the Ministry of Health, Labor and Welfare of Japan.

Thanks to Takegami's unremitting efforts, in 2021, he finally received four copies of his father's military service record from the labor ministry through the Nagano Prefectural Government. Two of them are covers labeled "Unit 1644 roster," while the other two, clearly stamped with the labor ministry's seal, contain two lines of information detailing his father's military service history.

Although there are only two lines and his father's name was mistakenly written in the registration, Takegami confirmed it was indeed his father through the correct home address and date of birth.

"More importantly, the copies of these cover pages proved to me that the labor ministry has a complete version of the roster of Unit 1644," he added.

With the copy of the cover as evidence, Takegami asked the labor ministry for permission to review the complete list of the roster, but the ministry refused on the grounds of protecting privacy.

The Japanese government's attitude towards the Japanese bacteriological warfare units deployed in China has always been vague, evasive or even denying.

Hideo Shimizu, a former member of the notorious Unit 731 who also lives in Nagano Prefecture, criticized the Japanese military for having done so many bad things, but the Japanese government not only showed no remorse but also wanted to pretend that these cruel histories had never happened.

"Although the government has not made any official statement, based on the information I have obtained over the years, I believe that they (the Central China Epidemic Prevention and Water Purification Department) are very likely to have conducted germ warfare and human experimentation," Takegami said, adding that "this is completely inhuman and should be reflected upon."

Takegami approached other experts and scholars, and together they continued to put pressure on the government. Eventually, the labor ministry transferred the rosters containing detailed personal information on members of Unit 1644, Unit 8604, and Unit 8609 to the National Archives of Japan in March 2024.

On May 14 this year, the National Archives of Japan made public a number of archives related to the Japanese army's germ-warfare units in China, including the three rosters containing detailed personal information on unit members.

From the discovery of his father's belongings to the sight of the previously classified roster of Unit 1644, seven or eight years have passed, and a part of this "lost" history has finally been revealed.

"I hope that the public release of the rosters can promote progress in related research, and I will continue to investigate to uncover the truth," Takegami said.