After The King of Iron Fist Tournament 2, the Mishima Zaibatsu used Nina as an experimental test subject for cryogenics research.  Fifteen years later, Nina was released from cryosleep and appeared in the third Tournament.  She fought through the Tournament while suffering from cryosleep-induced amnesia.

Since then, Nina disappeared from the reaches of the Mishima Zaibatsu and spent her days carrying out missions as a contract assassin.  To this day, she has been unable to regain memories of Anna or her personal life.

As a woman without memories or close relations, the only person Nina could count on was herself.  Carrying out her hits for profit was the only reality she could rely on.

One day, Nina received a new contract from a Mafia organization.  The target of the contract was Steve Fox, a boxing world champion.  With a little research, Nina discovered that Fox was a participant in The King of Iron Fist Tournament 4.  Nina set her sights on completing her new mission and infiltrated the Tournament.