The concept you have come up with, in an effort to avoid further increments in living expenses, seems like the worst of a number of choices. I too, would strongly recommend against such a move.
However, we have no information about you and your spouse at all, at the moment. Are both you and your spouse non-Japanese nationals? How long have you lived here in Japan, if you are not, and how long has the one of you lived here, if one of you is a Japanese national?
I would sugguest working on plans to increase income, rather than save costs--that will surely give you more leverage in the long run.