This is the Hongdae of Osaka. The Harajuku of Osaka. It's the area where all the cool kids hang out, so obviously it's the area where you need to be hanging out, too. The narrow streets lined with fashion boutiques, vintage clothes stores and graffiti art converge on a small central square (actually it's a circle) overlooked by a replica Statue of Liberty.
Spend a day wandering around, browsing the latest Japanese trends, and then perhaps grab some takoyaki and a bubble tea and sit in the square for some great people-watching.
To get there, take the subway to Nanba (なんば) or Shinsaibashi (心斎橋). America Mura is easily found on maps, guide books and Google street view.