Although it was supposed to go on sale September 21, it seems that Namco has released We Love Katamari early.
Or more precisely, Target Stores have put it on sale early. We've had multiple reports from people that have bought the game from their local Target brick-and-mortar stores.
Before you run out and check your local store, give them a call and ask them if they have any of SKU # 207121493 in stock. They can lickety split enter it into the computer and check.