New Game +
By clearing the game, you unlock New Game+. Your current level, Persona Compendium, Equipment, Play Time, and Maxed Social Links are all carried over from your cleared game. In addition, you gain access to the Monad Block and an optional new boss is unlocked. Consumable items do not carry over.
Reach the Top floor (252nd floor) of Tartarus. At 1/1 it will opened automatically.
To unlock the ultimate opponent you must clear Margaret's Request. Void Room will be automatically opened at 1/1. Clear it and Pandora's Door will open.