Julie Makimoto hails from Australia's Bakugan Valley, later settling in Bayview before Bakugan Battle Brawlers begins. Her childhood bond with Billy Gilbert blossoms into romance during the first season. As a Subterra brawler, she partners primarily with Hammer Gorem alongside Tuskor and Rattleoid. Julie exhibits a bubbly, extroverted personality with occasional scatterbrained moments, yet proves fiercely competitive in battles. Early admiration for Dan Kuso sparks jealousy-fueled clashes with Runo Misaki, though their dynamic shifts to friendship after Julie commits to Billy. In Bakugan Battle Brawlers, Julie bonds with Gorem after failing to find a talking Bakugan, later defeating Billy in a rematch. When Billy joins Masquerade, she nearly loses Gorem battling Komba O'Charlie and Billy. Determined to free Billy from Naga's influence, she triggers his defection by returning a childhood toy cowboy. During Clayf's test in the Doom Dimension, Julie conquers insecurities stemming from comparisons to her sister Daisy Makimoto, enabling Gorem's evolution. She stalls Subterra-Haos hybrids Rabeeder and Tricloid during Naga's arc and aids the final battle against Naga. Post-conflict, she releases her Bakugan as they return to Vestroia. During New Vestroia, Julie stays on Earth while Dan departs. She assists Runo's ill-fated dimensional transporter attempt, trapping Runo between dimensions. Initially lacking a gauntlet or Bakugan, Julie coaches Mira Fermin on Subterra tactics during Mira's duel against Gus Grav, contributing to Spectra Phantom's unmasking as Keith Fermin. Though Mira gifts her a gauntlet, Spectra excludes Julie from the Motherpalace mission for not being chosen by the Ancients. She reunites with Gorem after the Vestals' defeat but retires from active brawling when Gorem restricts battles to protect her. Alongside Billy, she resists King Zenoheld's Bakugan Termination System and Alternative Weapon System. In Gundalian Invaders, Julie moves to Bayview with Dan, working as a café waitress and school cheerleader. She mentors new Subterra brawler Jake Vallory, stressing individual battling styles over emulating Dan. Her activities include monitoring Bakugan Interspace and caring for injured allies like Linus. Zenet later impersonates Julie to deceive Dan. By Mechtanium Surge, Julie becomes a news reporter covering Bakugan events in Bakugan City. She delivers battle suits to Dan, Marucho, and Shun alongside Runo and Mira. During an assault by the Mechtogan Mechtavius Destroyer, Julie perishes alongside Runo, Mira, and others when it obliterates Bakugan City. This timeline is later averted through time manipulation by Dan, Shun, and Marucho.