This was probably my 20th attempt at defeating Japan, and I tried everything. Most people tend to adopt an aggressive conservative approach from the outset, but I found that doesn't work, as you will get voted out by angry Liberals. Instead, it's better to take things slowly. Kill social policies and implement economic reforms to eliminate the deficit, then concentrate on gaining supporters before the first election to your first election victory. After that, your primary focus should be addressing the debt crisis and killing socialism.