@pejak The weak JPY is good for exports and exports make up a large portion of the Japanese economy. It's even good for domestic companies that don't export as it makes domestic labor more price competitive with foreign labor.
Raising interest rates in Japan would make Japanese companies less competitive, would cost the government more money in interest, and would tank the Japanese economy because with higher interest rates people would stop spending.
So, where is the benefit to raising interest rates in Japan? There isn't one.