Embattled Japanese Defence Minister Tomomi Inada on Friday said she was resigning, after a series of gaffes, missteps and a cover-up at her ministry that have contributed to a sharp plunge in public support for Prime Minister Shinzo Abe.
Inada, 58, an Abe protege who shares his conservative views and had been suggested as a possible future premier, had already expected to be replaced in a likely cabinet reshuffle next week that Abe hopes will help rebuild his ratings.
Support for the prime minister has sunk below 30 percent in some polls, due to scandals over suspected cronyism and a view among many voters that he and his aides took them for granted.
Abe apologized "to the people from my heart", in comments to reporters carried live on national television after Inada announced her resignation.
He said Foreign Minister Fumio Kishida would add the defence portfolio to his duties, to eliminate any gap at a time when Japan faces tough security challenges, such as a volatile North Korea.
Abe, however, had drawn fire from both ruling and opposition party lawmakers for retaining Inada despite her missteps and perceived incompetence.
"He should have thrown Inada under the bus long ago. Doing so on the eve of a cabinet reshuffle only looks like desperation," said Jeffrey Kingston, director of Asian Studies at Temple University Japan.
The resignation coincided with a report of an investigation into suspicions that defence ministry officials tried to hide logs showing worsening security in South Sudan, where Japanese troops joined in a U.S.-led peacekeeping operation.
Critics said troop deployment in the dangerous environment violated conditions set for such activities in line with Japan's pacifist constitution.
No Japanese troops have died in combat since World War Two and the growing chaos in South Sudan fuelled concern.