More than 350 protesters gathered outside the Ministry of Foreign Affairs in the heart of Tokyo to express their outrage at the government's silence on Tuesday afternoon, carrying signs and banners reading "Silenced screams of Okinawan girls," "Restore dignity to Okinawa". Women" and "No more government cover-up of US troops' crimes," the Xinhua news agency reported.

According to local media reports, a 21-year-old US Marine from Okinawa Prefecture in the far south of Japan has been formally charged with non-consensual sexual relations resulting in injury in May, following the allegation of a member of the US Air Force for the alleged kidnapping and sexual assault of a 16-year-old minor in December.

However, the Japanese government did not reveal the cases until local media exposed them in late June, sparking widespread anger across the country.

"The Japanese government, especially the Ministry of Foreign Affairs, knew this, but preferred to remain silent. This is undemocratic. They are ignoring the people of Japan, the women of Japan and the people of Okinawa," denounced Mizuho Fukushima, head of the opposition Social Democratic Party, during his speech at the protest.

"While claiming to protect victims, the government protects criminals," criticized Suzuyo Takazato, leader of a civic group in Okinawa.

Hatsuko Aoki, a 76-year-old protester from the city of Nago in Okinawa, could barely contain her anger as she recalled witnessing her elders being threatened by the US military during her childhood.

"As long as American military bases remain in Japan, these incidents will continue to occur," the old man bellowed.

"I cannot forgive the government for hiding the sexual assault cases from the US military," Aoki told Xinhua, condemning the Japanese government for colluding with the US military to hide these crimes, not only to manipulate the election results but also to suppress the protests against the construction of the new Henoko US military base in Japan.

In the mid-June Okinawa Prefectural Assembly elections, the ruling Liberal Democratic Party (LDP) and its coalition partner, Komeito, who support the US Marine Corps Air Station Futenma relocation plan , won the majority for the first time in 16 years.

Representatives of multiple civil groups at Tuesday's protest emphasized that if the cases of aggression had been revealed before the elections, the LDP would have had difficulty securing a majority, indicating ulterior motives of the government.

Amid cloudy skies and drizzle, many citizens brought bouquets of flowers to the scene to show solidarity with the victims of the attacks. Among them was Rei Saito, who came to express empathy for her when she was young.

She said: "What is even more inexcusable is that the Okinawa police did not report the cases to the prefectural government. They seem to believe that they can act with impunity, a trend that is becoming more egregious."

Okinawa is home to 70 percent of all U.S. military bases in Japan, while accounting for only 0.6 percent of the country's total land area. Crimes committed by U.S. service members and non-military personnel have been a constant source of grievance for locals.

The tragedies continue to occur decades after mass protests in Japan when a 12-year-old girl was raped by three American soldiers in 1995. "Okinawa residents don't know how much similar damage they have to endure because of the Japanese government," lamented one protester.