[GoNative]

I don't find living in Japan to be expensive at all. Quite a bit cheaper than life in Australia these days. But I do fully own my home here so no rent or loan which makes life pretty easy and I do live in rural Hokkaido which is about as cheap an area to live in Japan as there is.
As sangetsu said where you live makes a big difference if you're only earning Y250,000-300,000 a month. Tokyo is not cheap but what what major city in the world is?