According to Cinema Blend on Jan. 21, 2013, it reported that in an MTV interview with Robert Rodriguez at the Sundance Film Festival about "Sin City 2: A Dame To Kill For" and confirmed Bruce Willis to return as John Hartigan.
It was discussed that with the stories within Sin City are being shot, one was finally complete and the others are still being piece mealed together as actors become available according to their scheduling.
Also, Joseph Gordon-Levitt, who also starred in "Looper" with Willis, has also been cast as a cocky gambler by the name of Johnny that makes an attempt to play against the biggest villain in the city at his own game. The story that Gordon-Levitt will be playing a role in will be "The Long Bad Night".
The reason Gordon-Levitt did sign up for the role was pretty much summed up in one word or name, "Rodriguez".
"Sin City" is based off a graphic novel by the author Frank Miller who is known for his rather dark, film noir-style comic book series. The environment in which the story takes place is a high crime ridden area where police are more S.W.A.T. than uniformed street cops. So the enforcement is taken up a notch in a city that's full of corruption and even common civilians could be considered highly dangerous. There are very few honest cops while the rest of the force are easily corrupted by positions of higher clout.