According to Japanese media reports, the Marine was arrested in connection with the alleged robbery and murder.

NHK World identified the US Marine as 20-year-old Devin Jacob Ballard, who is stationed at the US Marine Corps Air Station Futenma.

The victim was identified by police as 39-year-old Anna Yagi, a resident of Naha.

She was found dead inside a hotel room in Okinawa and was pronounced dead at the scene. Investigators said the condition of her body indicated that she had been murdered.

Police told NHK World that some of Yagi's belongings were later found abandoned near the hotel. Investigators are treating the case as a robbery-murder.

According to reports, security camera footage showed a man with a shaved head, who appeared to be a foreign national, entering the hotel with the woman and later leaving with her belongings.

Police said the suspect has denied the allegations. Investigators are continuing to probe the circumstances surrounding the incident.

Reacting to the case, Takaichi wrote on X: "I express my condolences to those who lost their lives in the robbery-murder incident that occurred in Naha City, Okinawa Prefecture, and extend my sympathies to their bereaved families."

She added: "Regarding this case, the investigation by the Okinawa Prefectural Police is ongoing, but I understand that a U.S. Marine Corps member has been arrested today."

"The occurrence of such an extremely brutal and heinous incident is a matter of profound regret, and as the Government of Japan, we have lodged a strong protest with the U.S. side, while firmly demanding maximum cooperation with the investigation, strict discipline among U.S. military personnel, and thorough measures to prevent the recurrence of such incidents and accidents," she said.

Takaichi said her government would address the case with the utmost care and diligence.

Meanwhile, the US Marine Corps expressed condolences to the victim's family and said it was cooperating with Japanese authorities.

"We are actively cooperating with Japanese authorities in response to allegations of serious criminal actions by a Marine assigned to the III Marine Expeditionary Force," CNN reported, quoting a statement issued by the US Marine Corps.