Actually there have been a few times when the LDP wasn’t in power
In 2009 the Democratic Party (of Japan) ruled the country. They were ousted 3 years later because like any Democrat they jacked taxes through the roof and got beaten in the 2012 elections.
https://en.wikipedia.org/wiki/2012_Japanese_general_election
OK - they have ruled 63 out of 67 years . Not bad , ey ?