As a Child, Niina had a curse put on her by an imposter posing as her uncle.

The Uncle was actually a famous wrestler who was known as the second son of Reno (Niina's Grandpa), unlike Reno's first son, he knew how to wrestle, (as Niina's dad mastered in Karate.)

The Imposter came into their home, posing as Niina's Uncle Roger, "Roger" Claimed that he lost an abnormally large chain of fights, causing him to lose his fame, his money, and his house, claiming to need a place to stay.

That night, the imposter murdered Niina's parents, and Niina's Brother. And the imposter put a curse on Niina that made her Horrible at Wrestling indefinately until the curse was lifted by a Curse Expert.

The reasoning was was because that the imposter actually is a master of all fighting styles, we're yet to know his name, but he was told by his futurescope (a device created to see the future) that Niina would be able to defeat him with the Wrestling style. so, he basicly went to change the time stream.

Niina still has this curse inside her, and it takes form like this, and torments her mentally, even making her go into her dark form and want to murder random people for bloodlust.

(I'm still a bit undecisive on this story, I may change a few elements.)

Niina ©: Me