Japan's Self-Defense Forces and Defense Ministry will undergo a comprehensive harassment investigation, the ministry said Tuesday, in a rare move taken by its chief after an allegation by a former female SDF member of sexual assault by colleagues.

The investigation of various kinds of harassment by a defense watchdog was ordered by Defense Minister Yasukazu Hamada about a week after Rina Gonoi, 22, submitted a petition of over 100,000 signatures to the ministry last Wednesday, demanding a thorough independent probe into the case that occurred while she was a member of the Ground Self-Defense Force in August 2021.

File photo taken on Aug. 31, 2022 shows former female Self-Defense Forces member Rina Gonoi (L) submit a petition with over 10,000 online signatures requesting that the Defense Ministry launch an investigation after claiming she was sexually assaulted during training for the Ground Self-Defense Force last year. (Kyodo)

Gonoi has alleged three male senior colleagues forced her to the ground by her neck, forced her legs apart, and repeatedly pressed their crotches against her at a training site dormitory in the northeastern prefecture of Fukushima. She claims to have experienced many other incidents of sexual harassment in addition to this particular case.

Hamada said at a press conference that he ordered the Inspector General's Office of legal compliance, a special unit under his control, to inspect harassment, including bullying and abuse of power, for "eradication," citing the increasing number of harassment cases among SDF members, a still male-dominated profession.

Regarding Gonoi's case, Hamada said a probe has been ongoing, adding he has dispatched a prosecutor who belongs to the Inspector General's Office of legal compliance, as well as a prosecutor assistant officer who is on loan to the ministry, to a GSDF unit in the northeastern Tohoku region to investigate the case further.

"Harassment is an infringement of basic human rights. It must never happen that harassment would harm the strength of the SDF," Hamada said. However, he avoided saying that Gonoi's allegations are what urged the ministry to decide on the envisaged all-out inspection.

To fundamentally review the ministry's countermeasures, a panel consisting of experts from judicial, medical, media and business circles will also be set up, according to Hamada.

The number of consultations to the ministry related to harassment acts inside the SDF was 2,311 for fiscal 2021, which ended in March this year, soaring from 256 for fiscal 2016, the ministry said.

According to the Defense Ministry's annual white paper of 2022, the number of female SDF members stood at about 19,000 as of March, accounting for 8.3 percent and up from 5.4 percent a decade ago.