Singing to the Hearts

Nikki was the start of changing hearts along side Persona - Umi. Nikki was only able to access Mementos as she had no clue about Palaces. Just when she was on her way to school - following Ren and Ryuji, that was when she stumbled first into her first ever Palace. Together - they would create The Phantom Thieves - until Nikki's secret is let out of the bag-what will happen now?