Monica is Crusher's younger sister.
She is the sole reason why Crusher learned to beyblade and joined BEGA. She had a serious illness, yet her family could not pay for her operation by themselves. Crusher signed up at BEGA because Boris had told him that he would pay for it altogether, if Crusher joined him. Her brother's determination to save her obviously made her very happy and she continually supported him.
Before his battle with Ray, she gave him a small, stuffed version of her as a way for Moses to remember that she was confident in him and that she would always be there to help, at least in spirit. Her operation took place at the same time that he was battling Ray, which pressured him because he knew he could not lose.
After the fight, Crusher went to visit her once the operation was over and that she only needed to rest.
In the end, she is safe and happy living with her brother.
- 'Monica' is Greek for 'Advisor'.