Gifted with the Force, Japhta Fett was raised in the Jedi Temple for the first thirteen years of her life. As a child, she was trained by Yoda alongside her contemporary, Sarolyn Lordan. There was intense rivalry between Japhta and Sarolyn, and Sarolyn's superior command of the Force left Japhta humiliated and vengeful. Japhta used to bully and taunt Sarolyn constantly. but Sarolyn handled it perfectly. She merely looked down at Japhta and walked away. Yoda despaired of young Japhta. She had no way of controlling the Dark Side within her, and it was making her weak. As her adolescence drew near, it was clear that she would never be chosen as a Padawan learner. After Master Bil-Kit Jinn had chosen Sarolyn as his Padawan over her, Japhta flew into a fit of rage and attacked both Sarolyn and Bil-Kit. The elderly Jedi Master subdued Japhta and she was expelled from the order.
Japhta fled the Jedi Temple and drifted down into the seedy lower levels of Coruscant where she earned a few skillin as an underage prostitute. This dangerous and highly illegal activity render her pregnant and she gave birth to a son. She was only thirteen years of age. Shortly after the birth of her son, whose name remains unknown, Japhta Fett was discovered by Darth Rakshas, who was searching for a suitable apprentice. Sensing the Dark Side bubbling within Japhta, Rakshas took her in and trained her as the Hand of the Sith, his eyes and ears and an extension to his own dark will. Japhta's son was given away for adoption. Nurturing the hate and anger that had built up in Japhta, Rakshas turned her into an efficient and ruthless killer whist he hid her from the Jedi by clouding their vision.
Taking the name of Lord Koraetor Mandalore, Darth Rakshas built up MHG and employed Japhta Fett as his personal troubleshooter. Posing as Mandalore's lover, Fett led the fashion trends and was always seen at the most exclusive parties and functions where she mingled with the cream of Republic society. Mandalore and Fett became the closest thing to royalty possible in a republic. At MHG's height, Mandalore was one of the richest men in the Republic and certainly the most powerful, but this was not not enough for Japhta Fett. She wanted supremacy.
Japhta had not forgotten Sarolyn, and she would dream of bringing the severed head of her former nemesis to Darth Rakshas. This opportunity came sooner than she had expected, for Sarolyn had been sent to spy on Mandalore and was right under her nose at his Country Residence on Naboo. Japhta set a trap for her but Sarolyn was too clever and escaped. Japhta knew where Sarolyn was headed, so she took a faster ship and reached the MHG research institute on Despayre before her. There was a showdown between the two girls as they engaged in a vicious lightsabre duel. Japhta Fett had killed Bil-Kit Jinn on Sorensia, and now she was going to fulfil her destiny and destroy Sarolyn Lordan. Japhta's place as a Dark Lady of the Sith would be assured. Japhta had almost succeeded, and would certainly have killed Sarolyn had it not been for a mysterious beast that was lurking in the undergrowth nearby. As Sarolyn watched in disbelief, this creature leapt on top of Japhta and crushed her, killing her instantly.