UPDATE: Bloody hell! It's just BloodRayne Betrayal coming to Japan.
UPDATE 22/04/2014: Well, this is disappointing. Apparently that BloodRayne countdown teaser is just for BloodRyane Betrayal, WayForward's bite-'em-up from 2011. It looks like it's only now coming to Japan on 1st May. That's great for Japan (it is a pretty good game), but not as exciting as expected.
ORIGINAL STORY 17/04/2014: Guilty Gear, BlazBlue and Persona Arena developer Arc System Works has teased a new BloodRayne game.
The studio's official Japanese site currently hosts a large promotional image of a scantily-armoured woman bearing a medallion with the BloodRayne symbol on it. This upcoming project is abbreviated "BRCS", suggesting that the "BR" stands for BloodRayne, while a counter currently notes that we have six days left until the project's official 23rd April reveal.
Given Arc system Works' resume, it suggests that this will be a fighting game, but that's only speculation. Arc System Works has branched out of its fighting game wheelhouse on occasion, as it did with the Contra: Hard Corps prequel, Hard Corps: Uprising. That game followed WayForward Technologies' Contra 4, just as this new BloodRayne game will follow WayForward's 2011 bite-'em-up BloodRayne: Betrayal.
Now what could the "CS" stand for?
BloodRayne... Counter-Strike? Championship Slayers? Cruel Seductress?