This is very interesting, it seems we are going to get some Korra shorts set in time periods we have not seen yet.
Nick.con have just premiered a new web series called The Legend Of Korra Republic City Hustle online. EDIT/ Korra Nation have confirmed it is a 3 part series.
You can see episode 1 here. It is on Nick.com so anyone outside of USA should use a program like Tunnelbear to access it.
I just watched it and I am very impressed, it is nicely animated in a different style showing us life for Bolin and Mako on the streets of Republic City a few years ago. It is nicely voice acted too and seems like the perfect way to hype up Book 2.
This is the perfect way to visually fill us in on their backstory. In this episode we see the scamming that they have to do to survive, then their first meetings with Toza who is revealed to be a former Captain of The BoarQPines team. He takes a bribe to purposely lose the match, Bolin is upset at this while Mako just accepts it as a harsh reality.
Episode 2 by the looks of the preview image seems to hint at how Bolin found Pabu, which we know from the Art Book was him saving Pabu from a nasty pet store.
I am impressed so far, what about you?