That afternoon, Guidel talked to Leona. As if he was predicting the future, Guidel puts his hands on Leona's shoulders, and tells Leona that she must fight against her own destiny, no matter how cruel and sad it may be. Night falled, and all was calm. However, Leona began to feel sick, and her head ached a lot. Her family began worrying, and then, Leona coughed up blood. Guidel was shocked. It was signs of the Riot of Blood! And since Leona was never taught how to control the Orochi power in her veins, the consecuences could be terrible! Everybody tried to calm her down, but soon, Leona's eyes were lost, and she began to howl and sneer. It all happened very quickly...blood, screams, and then, nothing. Most of the villagers ran away, fearful of the wrath of the child. But Leona was thirsty for blood, and managed to get some of them. After many deaths, Leona was alone in the ruined village. She was stained with blood all over. Then, Goenitz came near the child. She puts a hand on her head, and tells her that she would go back to sleep again, and that she would only wake up again when the time comes. But, she would wake up in good company, so there was nothing to worry about. Goenitz goes away, and Leona is left with no memory of her past, due to the mental overrush she had when she was in her Riot of Blood self.

Leona began to walk with no particular destiny in the jungle. She was then found by an army man. His name was Heidern, and he took her back to headquarters. Heidern asked her so many questions, but Leona remained silent. Realizing it was useless to talk any further, Heidern decided to keep her at the base for some time, and then send her to an orphanage. However, when Heidern came back from a mission, he noticed how Leona slashed a tree to the ground. Surprised at this display of power, Heidern thought it would be better for the girl to stay with her and train as a female soldier.

Leona began her training under Heidern's orders. She learned all of Heidern's techniques, due to her incredible facility to cut things down with her hands. Heidern was surprised at how much Leona progressed, as if she was predisposed towards fighting... Anyway, it was not until 1996 when Leona received her first official mission order: she was to take Heidern's place in the Ikari Team that would participate in the King of Fighters tournament. Her new partners would be Heidern's favorite mercenaries: Ralf and Clark. Their mission was to investigate Geese Howard, the Southtown mob leader who has entered the tournament in search of something important (and it is known that anything Geese seeks will be something very bad). So, the new Ikari Team began their mission in the tournament. It was all going fine, until the finals...

Heidern orders the Ikari Warriors to go to the stadium where the finals are taking place in order to investigate any possible incident by Geese. While there, however, the stadium just got wrecked when a strong gust of wind blew. Leona was still reeling, when she felt an ominous presence. It was so familiar...then, Goenitz appeared. While he was fighting Kyo Kusanagi, Leona began to remember so many things...blood, screams, death. She began to lose her cool, and Ralf and Clark had to calm her down. Then, when Iori Yagami appeared, Goenitz laughs and tells Kyo that both him and Leona are of Orochi blood! Leona was shocked, and so where Ralf and Clark. Even when Goenitz vanished after being defeated by Kyo and Iori, Leona remained full with doubts and fear, with no idea of what to do...

By next year, Leona was so tense that she barely could do anything right. During a mission in a burnt village, Leona revived moments of her dark past when she saw a fearful kid trying to run away from her. The mission was almost a failure thanks to Leona's distraction. Afterwards, Ralf bids Heidern to give them a suspension period so they can go to the King of Fighters tournament to distract Leona a bit. They did, but Leon was afraid that she may kill Ralf and Clark, and go out on a rampage. She also had a bad feeling about the tournament. Her fears became real in an instant. During the final laps of the tournament, Leona began to feel sick again. When she began coughing blood, Leona began to panic. Ralf and Clark tried to keep hold of her, but once again, Leona entered her Riot of Blood self, and goes berserk. Along with Iori, both begin going on a killing rampage. Ralf and Clark then decide to go after Leona and take her back. Leona manages to go back to normal with the help of her friends. When she wakes up, Leona tries to kill herself so that she won't cause anymore trouble. However, Ralf stops her and tells her she's not alone anymore, not as long as they are there with her. Then, Leona goes back home with her friends, ready to start a new life.

Leona finally finds some mild happiness after the Orochi menace ceased to exist. Enjoying more time with her partners during several missions, Leona also manages to control her hidden Orochi blood somewhat, and use it to become ever stronger! After quite some time of not fighting seriously, Leona is commanded by Heidern to participate in the King of Fighters tournament again, but she gets to have a new companion: another female soldier, Whip. Leona quickly finds a lot in common with Whip, as they seem to be very reserved, and not too talkative. However, they seem to get along quite well, which sort of gives Ralf and Clark something to worry about...after all, it's not good to pair up two violent women against two poor mercenaries!

Once the Krizalid project is dealt with, Leona and the rest of the Ikari Warriors are more than ready to do battle with the true menace behind Krizalid: the NESTS cartel. Their commander, Heidern, reports that he and his fellow comrade, Ling, will take care of the organization of the next King of Fighters tournament in order to lure NESTS out of there hole. Leona is considered to be of major importance, and so, the unit is dispatched to Southtown, last location of the NESTS.

There, Leona feels something at unease. He urges her partners to hurry towards the designated meeting point, informed by Heidern. Leona and the others hurry to an abandoned factory in the industrial zone of Southtown. There, Heidern is found, badly wounded, but with life still in his body. Leona helps her foster father up, and Heidern thanks her. Leona tells her commander that it was finally time for her to do something for Heidern. Heidern smiles, but is soon removed when he notices that Whip is missing. Heidern contacts Whip with desperation, but to no avail. Leona, Ralf, and Clark escape with Heidern in the nick of time: the Zero Cannon, NESTS' ultimate weapon, destroys the whole city of Southtown with one huge blast!

After scouting the area for possible survivors and traces of NESTS, the Ikari Warriors sorrowfully return to their base. Leona is, once again, depressed for the lost of a fellow friend, who she thought she could save if given the chance. Soon enough, Heidern shows them a video that Whip had left them as a reminder. In it, Whip bids her former partners farewell, and confesses her deep affection for all of them. She hopes to meet again soon, and gives a final salute. Leona, for once, finally manages to break open a smile, and shed a tear for her fallen friend.

As her life keeps going on, Leona now focuses her spirit in taking down NESTS, as ordered by her commander and foster father, Heidern. But in every operation that she carries out, even with her amount of skill and stealth, she does not have much success inflitrating the several bases of HQ around the world. Leona thinks it's weird that these places were abandoned in such a short notice. Attending to Heidern's call, Leona hears from her commander that Whip is still around, and has sent them info regarding NESTS. It seems that NESTS is going to host the next King of Fighters tournament, and go public. Leona knows NESTS is up to no good, and will help Heidern in all she can to take them down.

Leona keeps her real mission of investigating NESTS under wraps as she continues to fight in the tournament. She is happy to see Whip once again, even though she has to see her as a rival, as Whip is now participating with K' and the other NESTS renegades. However, as usual, Leona keeps her emotions to herself as they continue tracking down the trail of NESTS. They finally manage to locate their main HQ, which is no other than a base located in outer space! Leona now has to settle herself with watching the whole fight from afar. In the end, the space station of NESTS comes crashing down, and Leona's mission is considered over. Leona inmediately asks Heidern about Whip's whereabouts, and Heidern confirms that she managed to escape the space station in time, but there was also some disturbing news concerning Whip: she was just another clone created by NESTS' diabolical bio-technology! Leona knows what it is not being able to know oneself, and she hopes Whip manages to pull it together one day, as she takes out on another mission along with her loyal comrades, Ralf and Clark.

Leona is very quiet, and does not like to talk too much. She has a very cold attitude, and other than Ralf, Whip, and Clark and commander Heidern, Leona does not talk to anyone. She seems fearless from the outside, but she's always afraid that she may cause harm to her friends. Leona also seems to hate the sight of blood ever since killing her family, but when she fights, she seems to always get covered with it. She feels lonely, but knows that Ralf, Whip, and Clark are always behind her.