Japan having Democracy is a unique circumstance of modern times showing the value of a democratic process for legitimacy.

Japan was ruled by a single authoritarian dynasty from the Sengoku Jidai to the Meiji Restoration. This dynasty took intensive and totalitarian interest in it's population and resources, including death penalties for people who would cut trees in a sacred forest (so that Japan didn't lose all of it's lumber supply), and was significantly isolationist. After which, it was replaced by an Empire under a royal monarchy, after which it was replaced by Fascist Militarists, after which it was replaced by Authoritarians who embraced Keynesian (Fabian Socialist) Economics.

They moral authoritarians, even totalitarian, and have very strict focus on family because of an ancient Clan culture. It's very difficult for socialists to make cultural headway in Japan when they already have Communist China as a rival, and their own form of authoritarianism is already culturally ingrained.