While Japan played down any negative impact from the political upheaval in South Korea, the possible departure of President Park Geun-hye could change Japan's calculus on both bilateral relations and the shifting regional security landscape.

One issue that a resignation could potentially influence is the complete implementation of last year's deal to resolve the issue of Korean "comfort women" who were forced to work in Japanese wartime military brothels.

"Tokyo will not make any comments as it is a domestic matter (for South Korea)," Deputy Chief Cabinet Minister Kotaro Nogami said at a daily news conference Tuesday. "But I would expect both countries to act in accordance with the agreement."