Also to be remembered is the Japanese occupation of China and the atrocities such as the Rape of Nanking.
Japan seems to be aging and in decline. China is but a teenager with growing economic muscle. In the long run, Japan will be a China hegemon.
The great grand children of the rapists will buckle to China
Precisely, all the more reason for a desperate country to pursue this route. Nukes are relatively inexpensive compared to maintaining a conventional military and a demographic multiplier.