OMG, I detected a China threat alert from @Nihonjin1051 . Looks like it will be a new Cold War in Asia after all.
That is significantly less than China's foreign exchange reserves.
Threat from China? No.
As for foreign reserves, we have close to $3 Trillion and China has around $4 Trillion.
For a country as ultra developed as Japan, that is great since we can put more in international and foreign investments (not that Japan is the largest creditor nation). China, on the other hand is still developing and its forex will be used to develo much of the country. Not to mention that there are 128 million Japanese vs 1.4 billion Chines. Per capita wise, Japan is pedestaled.