Japan's status in the first world war as a combatant that was under no real threat allowed their economy to grow rapidly as they found new markets, and they massively expanded their shipping and exports. The urban population grew rapidly, the roads were modernized and the railways massively expanded. In the 1930's automobiles became popular, especially in Tokyo where they outnumbered rickshaws for the first time. The amount of universities increased, and the number of students tripled. The new wonders of cinema, and radio were becoming popular in Tokyo, which was quickly becoming a western style metropolis. However, this new shift to urban populations did have some downsides, agricultural incomes fell in the rural areas, and there was a growing disparity between rich and poor. The incomes did grow, but by 1938 they hadn't reached their pre-depression level yet. The jobs in manufacturing, which Japan had always lacked, grew to over 7 million. Japan also increased its energy output and invested heavily in electricity, and even in the most rural areas, the majority of the population had access to electricity. So Japan, especially in urban areas had a very decent standard of living before the war started. They were still modernizing and so the standard of living wasn't yet on par with the Western nations, but it was coming close.

Now I don't know really know a whole lot about Japan's economy and standard of living after the American occupation. Japan was hit very hard in WW2, but given the reforms the American occupation authority introduced and the fact that it was 1952 and living standards generally increase with time, I think it is fair to say that the average Japanese citizen was much better off after the American occupation than they were before.

Source:

A History of Japan by L.M Cullen

The Economics of WW2 by Mark Harrison

If you mean purely in economic terms, they were probably on the whole better afterwards. In the last two years of the occupation food rationing became less stringent and the Korean War started a boom in Japanese manufacturing. On top of this, the occupying forces had redistributed land to the peasants that farmed it and permitted industrial workers some limited organizing rights. So 1952 was a relatively good year in Japan, purely in terms of productivity.

In the broader human sense, both the war and the occupation were brutal on Japan, and I for one would rather have have lived before WWII. So many cities were destroyed, so many people died, there were years of unemployment and misery and despair and alcoholism. Japanese civilians didn't even have recourse against rape and gang-rape. The Home Islands were denied adequate food to support the population until 1949; a policy of deindustrialization was pursued for a few years. On the whole everything that is written about the occupation sounds very unpleasant and I don't think that the manufacturing boom in the first year after the official end of the occupation could really compensate for that.