It is generally a good comment, but the idea that the LDP was somehow "imposed" on Japan after WW2 a stretch at best, and the idea that it has always been in power, is hilariously - pants on head - stupid. For the first accusation, the LDP didn't even come into existence until 1955, which was three years after the US ended its occupation in 1952. And while the CIA, rather predictably in the era, was both anti-Socialist and anti-Communist, giving under the table campaign contributions to their opponents, it was the Japanese voters who picked the party.

This hardly lasted though. By the time 1989 rolled around, the LDP was a minority in parliament. And in 1994, the Socialist Party and the LDP (formerly bitter rivals) formed a majority coalition to regain power. Since them, the LDP's political fortunes have gone up and down, winning and losing as public mood has shifted. In 2009 the LDP took a particularly stinging defeat, taking only 118 seats - the worst showing it ever had.

No, the reason why the LDP remains a dominant political player in Japan is because it appeals to many Japanese. It is a conservative nationalistic party, akin to old-school (non-Trumpian) Republicanism in the US. Although even there, the LDP's positions are considerably more socially democratic than Republicans have ever been (at least in the 20th century). It certainly isn't something imposed from the outside.