Nina absolutely loves money. With a passion for wealth and expensive objects, you, as the player, will have to buy her a variety of gifts, such as cars. This will, however, cost you billions of dollars unless you choose to use Diamonds.
As you get to know her and the relationship flourishes, Nina grows to care for you somewhat. As the game progresses, Nina eventually disguises herself as you/impersonates you after an accidental double-booking with Elle and Fumi. 