Even if Japan lets market rates rule, interest rates may not rise much. As foreign bankers are all too aware, the Japanese have more money than they need. Even then, ironically, Japanese corporations have already been borrowing massive amounts abroad. The Japanese occupy the most enviable of positions. Thus the corporations of the world's most capital rich nation have been able to issue massive levels of convertible bonds in the Euromarkets at unbelievably low interest rates.
American corporations pay more.
Thus the Japanese are borrowing abroad at low interest rates and investing overseas at high interest rates, a financiers paradise. That is what they are supposed to be doing. In contrast what is the creditworthiness of corporations that seem to be unstoppable in the worlds markets.