Most likely you get another 2 less popular characters for free within a limited period just like before, at least in Asia.
Only the download. The ones who really play it probably just 1/5 of it.
During the celebration of downloading goals, KT allowed the possibility to download for a limited time a character and being able to play with it forever (so it's to all the effects free purchase that unlock a character and not a simple limited trial). Also, Core Fighters' free trials allow the possibility to play with all the roster and not only the less popular, there is a rotation that get each character of the roster and then starts again from the beginning. The only exception was that the DLC characters ended to be added to the free trial selection only in the last cycle (of course they wished to keep a certain priority to them).
I agree however that the number of downloads doesn't mean anything about the effective popularity of the game or the number of the people playing it.
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From Gamefaq's thread about the free DLC for December:
It's two free costumes designed by Tamiki Wakaki for Kasumi (Ten - heaven or sky) and Ayane (Ha - Dominance or Rule).
http://www.gamefaqs.com/boards/835976-dead-or-alive-5-last-round/72971686?page=2
If this is right of course they are going to be two new costumes and not the ones from the Tamiki Wakaki pack.
