According to FINANCIAL TIMES, since the largest number of patent applications (94,079) are filed in the world, the world’s innovation hotspot is Tokyo - Yokohama area (cluster).
This results come from the study which analysed the addresses of inventors named in all 950,000 international patent applications published between 2011 and 2015 under the Patent Cooperation Treaty.
It seems that this result was due to the fact that there are many laboratories of Japanese and foreign companies in this area.
By the way, the second place is the Shenzhen - Hong Kong cluster, which is said to be "Silicon Valley in China", and the number of patent applications filed in the same period was 41,218.
The third place is Silicon Valley (San Jose - San Francisco cluster) in the United States, and the number of patent applications filed in the same period was 34,324.
The fourth place is Seoul - Daejeon cluster, and the number of patent applications filed in the same period was 34,200.