Singapore is a de-facto one party state where it is notable when an opposition party wins any seats whatsoever in the legislature. Three of Japan's last four prime ministers were from the Democratic Party of Japan, which is not the Liberal Democratic Party, which is the "same party" you're thinking of. The Japanese government, for all its numerous faults, runs hotly contested elections on a more-than-regular basis which can, and do, result in "voting the bums out."

Whether they have "democratic efficacy" is a bit more of an open question -- some observers of Japanese politics might opine that it is a rare, rare Japanese government where the legislature or prime minister exercise proximate control of the levers of sociopolitical power.