To gain the 12 hearts needed go to the mall. Buy an Apple, Tangerine and a Watermelon. Go on a date with Nami, Robin and Nobara.
Give them the foods Nami-Tangerine, Robin-Apple, Nobara- Watermelon.
This bust there trust and Now you can use them in the hole in the wall in the back Ally. Each one gives you a heart.