When Prime Minister Shinzo Abe picked confidante Tomomi Inada to be defense minister last August, she was widely seen as having the potential to someday become the first woman to hold the nation's highest office.

But the once-promising future of the 58-year-old former lawyer has become increasingly uncertain after a year dominated by missteps that many attribute to incompetence and character flaws. These culminated in her resignation over an alleged cover-up scandal on Friday.

"I won't say Inada is finished as a politician, but I don't have the impression she has the potential to become a leader who can manipulate situations to her advantage ... or appeal to the hearts of the voters and win them over," said Junichi Takase, a professor of political science at Nagoya University of Foreign Studies.