User blog comment:Master Sima Yi/Assassinews 28-02-'13 — Assassin's Creed IV: Black Flag revealed/@comment-4829046-20130301065828/@comment-1153722-20130301070238

It should have just been Assassin's Creed: Black Flag, since this doesn't have anything to do with Assassin's Creed III either. But the reason that they put in that "IV" is surely because the game is about a new ancestor, and they want each game with a new ancestor to be a numerical title.

Though how do you get to say nothing about what happens next? o.O