I'm in a similar position to someone who posted earlier... I have 15 3/4 hearts. I've explored every area except for one white square at the southern portion of the northern overworld. The last poster said "never mind, I searched and found that last heart piece."
Unfortunately, I can't find it anywhere. I've searched every single screen and have come up empty. I know, it's pretty hard to say which heart piece I'm missing, since I've got 20 of the 21 containers, but perhaps the other poster could point me to where his last one was, or someone could let me in on maybe one of the trickier ones I might have missed?
thanks!