For Japan, GNP might be more to show the wealth than GDP. Whereas, China has a lot of FDI, but has less investment abroad.

Sometimes I think the number of GDP is a little confusing. Japan is a defeated country in world war II, which means it must build up the new industry on ruins. Besides, it has to bear lots of war indemnities. How could it be so strong just after the war while now it is regressing compared to other neighbor countries?
After all, I think Japan's economy is much robust, as it owns many high sci-tech products and is well-industralized with many manufacturing companies. Other Asian regions, although may be wealthy, sound much more like places full of entertainments and are prosprous in financial market.

After disasters, like war or tsunami, GDP always surges. It is famous "broken window theory" as peopel have to invest more (by government or individual). Actually, based on growth theory, the GDP growth rate always converges to a stable level, if no exploding tech comes out like internet industry.

I agree with you that Japan well established its economy on high tech, but Korea and Taiwan also do. They are the same. Had you place close scrutiny into the graph above, you may conclude that Taiwan, Korea and Japan are in the same category; while Singapore and Hong Kong must be another eastern Asia miracle.

Singapore and Hong Kong are ports, economically speaking, not a full-fledged nation to sustain all government functions like inequality mitigation, military service supply and disaster prevention. Their growth mechanism should be specific and not so general as Japan's is.