Julie is a 12 year old girl. She may come off a bit scattered but Julie can compete with the best of them at Bakugan. Julie would best be described as a little princess and in conversation, she can be a little vacant. She is bubbly, extroverted and adores Dan Kuso. She also hates Runo out of jealousy, but they end up good friends. She is his number one fan. Julie lives in the isolated Bakugan Valley, Australia.
She is childhood friends with Billy and when he joins Masquerade she is crushed. She does whatever she can to free him from Masquerade's grip, which she does. When she is tested by Clayf she must battle against an illusionary version of her sister, Daisy Makimoto, making her think she wasn't special and how Daisy would always out do her at everything, but then she realized that she is special and doesn't need to compare herself to her sister. She battles Dan first to get Drago to evolve and it has been revealed that in the rankings she has moved up to eigth place. She and Hammer Gorem are defeated nevertheless, Dan hesitates a little bit since he didn't want her to fall off Hammer Gorem but Dan finally used his ability and caught Julie before she fell.
When the Brawlers were in Vestroia Julie and Runo stayed behind in the Sub Terra/Haos world to slow down the Sub Terra-Haos Hybrids Rabeeder and Tricloid. Since they challenged them to a race Runo and Julie stalled them until Dan and Drago reached the portal, they stayed behind however. She later faced Tricloid again alongside Billy and Nene and defeat her, later forming a boyfriend/girlfriend relationship with Billy. Julie usually battles alone but she has partnerd with Dan, Runo, Shun, Billy, and Nene.
 New VestroiaJulie is now 15, wearing new clothes like all others, she also walks around half-naked. She is seen with Marucho in the first episode, spying on Runo and Dan. When Drago asks for help everyone volunteers but Drago asks the girls and Marucho to turn around Dan, Drago, and Marucho enter the portal. Julie and Runo are furious as the the boys ditched them. Julie is later seen talking about Billy at the diner where the girls work restating the romantic bond between them. Julie returns to help Runo to get to New Vestroia and help Dan, Marucho, and Drago. She was also alongside Mira Clay in a battle with Gus Grav when Mira challenged Spectra to take off his mask if she beat him in a battle. Julie is then forced to enter and help Dan and the Bakugan Resistance, but after Lync entered, those who were able to enter in the Transporter must have Gauntlets, being Dan and Baron. However, Julie and the other friends couldn't enter. When Mira returned in the next season she gave Runo,Alice and Julie Gauntlets.
In episode 37, She and Billy battled against Ace, but even with the combined power of Gorem and Cycloid, they couldn't defeat him.