Just hours before his announcement last month that he would dissolve the Lower House for a snap election, Prime Minister Shinzo Abe was blindsided by his biggest political adversary of late: Tokyo Gov. Yuriko Koike. The telegenic, populist governor had upstaged Abe by announcing that she would create a new political party, Kibo no To (Party of Hope), in a bid to boot him out of power in the Oct. 22 vote.

But by the time the race officially kicked off Tuesday, what was initially heralded as yet another example of Koike's political showmanship had quickly lost steam, with Abe's Liberal Democratic Party forecast to avoid the worst-case scenario it once feared.

"It's possible that (Abe's) ruling coalition will survive the election pretty much unscathed," said Kazuhisa Kawakami, a professor of political science at the International University of Health and Welfare.