I found this at the Supreme Prosecutors’ Office ROK website. You can download a PDF file.

So the latest figures available were for 2014. The numbers (from left to right) represent the following (for false accusation):

Total number of cases (4,859), Number of cases per 100,000 of the population (9), Total arrests made (4,110), Arrest rate (84.6%), Total number of individuals arrested (6,349), Men (3,964), Women (2,170), Unknown (215), Legal entities (11).

I also found a recent news article saying that 16.7% of sexual violence crimes (e.g., rape, groping…) investigated ended up as being “groundless” (in 2014).

Thanks for reading!

ADDED: According to the former President of the International Criminal Court (ICC) Song Sang-hyun, the number of “false accusation” cases per 100,000 of the population in Japan is about 1.