Yuan's experience of doing his master's in Japan's Kanazawa University also helped him better understand the country and its people: "The Japanese have a very deep sense of crisis, and lay a lot of emphasis on potential risks." Therefore, he says, China should be aware of the risks, but not be over-cautious. At present, China is mainly buying short-term Japanese debts, which is not as risky as it appears to be. After all, Japan is different from Greece.

Interest is indeed the primary concern. The interest rate of Japanese bonds is very low compared with US and European bonds. The interest rate of 10-year Japanese bonds has fallen below 1 percent, while that of the US is still 3.6 percent. Besides, the value of the Japanese yen against the US dollar has been rising for a long time, and Tokyo may possibly take measures to depreciate its currency further to stimulate its economy. That is another risk of buying Japanese bonds - there is always the risk of the assets shrinking.

But Yuan says China should see the affair in its entirety. The two other main financial products, the euro and the US dollar, have their problems, too. To cope with economic recession, the US has issued too many banknotes. It's almost like "dumping dollars from planes and helicopters", Yuan says. This will cause inflation in the long run, and those who have their assets in US dollars may see their holdings shrink.

Currently, China holds a large number quantities of US bonds. But it should not put all its eggs in one basket. The State Administration of Foreign Exchange, in charge of China's overseas investment, said in a recent press note that it would adopt a strategy to diversify its foreign exchange holdings in order to make its investments more secure. Now, when the Europe Union is suffering from a sovereign debt crisis, Yuan says, Japanese bonds are a relatively good choice, at least in the short term.

Another problem China may face if it buys more Japanese bonds is not purely economical. While Tokyo is trying to promote its debt sales, many media outlets in Japan have expressed doubts over China's real intentions, fearing that Beijing may sell the Japanese bonds it holds suddenly to "deal a big blow" to the country's economy.

But Yuan says the purchase of Japanese bonds by China should not be politicized. "Every investor seeks good returns." By purchasing more Japanese bonds, China will help propel Asian economic integration, and that would certainly be more beneficial to Japan.

Economic unity requires intimate communication and cooperation between two countries. And by buying more Japanese bonds China has taken a vital step toward bilateral cooperation.