I've just been notified by Google that PCDB S*D*K* Solver has been removed from the Google Play store in Japan. Searching the web, there seems to be a concerted campaign by a Japanese company to remove any app with that word in its title, other than those they own, from the Japanese market. Surprisingly, the Lite version (free) wasn't mentioned, but just to be on the safe side I've removed that from the Japanese market too.
There doesn't seem to be any such pressure elsewhere in the world.