China-Japan forex reserve comparison

Both China and Japan are the holders of massive foreign exchange reserve, taking the top two slots in the world rankings. Interestingly, great concern has been raised only about Chinese reserve, whose massive amount and continued growth has been blamed for the appreciation of Chinese currency and the inflation pressure, among others.
I think the reasons could be traced to the sources of reserves in both countries. According to the Bank of China research fellow Wang Yuanlong, the sources of forex reserve could be divided into two parts: credit-based and debts-based. The former is reserve from current account with the latter from capital account. China, like most developing countries, used to have more debts-based reserve, due to the influx of direct foreign investment. later, the rights-based reserve increased a lot. However, during 2003-2004, the debt-based reserve rebounded greatly due to the influx of hot money or international speculative short-term capital.
Another analysis of Chinese forex reserve is divide them into mainly three parts: trade surplus, foreign investment, and hot money. The latter two accounted for a very big percentage of the Chinese total reserve. But according to Weng Xueqin(2007), Japanese reserve is largely different in terms of sources, with a majority coming from trade surplus. The foreign investment accounts for a very small proportion of the reserve.
Besides, Japan has a surplus of capital due to its strong economy, and need to invest to keep their value. Due to the very low interest rate and bearish stock market in Japan, most of the capital moves out of Japan and invests in foreign national bonds. On the contrary China fall short of capital and have to rely heavily on foreign investment.
The foreign reserve doesnot represent the disposal wealth for China, whose reserve has a large porportion of foreign investment and hot money. But it is not the case with Japan.
The two countries' differences could be also found in the way of reserve management. Japan has done well in maintaining the value of reserve, while China has has been set back by misconception on the reserve, thinking the more reserve, the better for national economy. They also think forex reserve should not be used except at the crucial moment. So such misconception have led to the overgrowth of the reserve, and consequent sideeffects and risks the country face today.