As of this week the sales gap between the PS4 and PS3 is under a million units sold in Japan. The PS4 definitely won't catch up, nor will it shrink the gap much further before it is discontinued. But each week the gap will get a little smaller.
It is still a disappointment that Japan is one of the few regions where the PS4 under performed compared to the PS3 but at least it wasn't the dramatic industry shifting collapse seen from PS2 to PS3.
http://www.youtube.com/watch?v=F1gWECYYOSo
Please Watch/Share this video so it gets shown in Hollywood.