Things are a little better in purchasing power per capita terms [2], but not by enough to make a difference.
[1] https://www.google.com/publicdata/explore?ds=d5bncppjof8f9_&...
[2] https://www.google.com/publicdata/explore?ds=d5bncppjof8f9_&...
Yet in 2012 it was $800B more than in 1995?
From your graph it has been mostly been stable.
I wonder if any developed countries middle class is faring well currently?
From what I saw, the whole place looked middle-class, and like everyone was doing fine. I think I might have seen one homeless person the whole time I was there (and I'm not sure about that; they were just begging, and didn't have a bunch of stuff with them); I saw more poverty in Germany, and I see far more in the US.
Japan's middle class might not have as much disposable income as it did in the 1980s, but from what I saw, it wasn't doing badly at all. It certainly looks a lot healthier than the US's middle class.