Marucho Marukura, nicknamed Marucho, serves as an integral member of the Battle Brawlers throughout all seasons, culminating in *Bakugan: Mechtanium Surge*. Beginning as an eleven-year-old intellectual specializing in the Aquos attribute, his wealthy background is marked by extreme obedience to his parents born from fear. His journey with the Battle Brawlers cultivates independence while preserving his respectful nature, leading him to reconcile with his past understanding that his compliance stemmed from a desire to please. He gains his first Guardian Bakugan, Aquos Preyas, when Preyas disrupts a housewarming party. Preyas later evolves into the unique Angelo/Diablo Preyas, multiplying during evolution so Marucho retains both forms. Preyas is temporarily lost to the Doom Dimension during a battle with Klaus von Hertzon but is later recovered. In *New Vestroia*, after Preyas is captured by the Vestals, Marucho partners with Aquos Elfin, whom he encounters in the jungle. Elfin proves her worth by aiding him against Vexos member Mylene Farrow and later evolves into Minx Elfin following the infusion of Attribute Energies from the Six Ancient Warriors. Marucho aids the Resistance against the Vexos, contributes technological expertise, and helps develop Battle Gear like JetKor for Drago. Upon defeating King Zenoheld's Alternative Weapon System, he returns to Earth with the Resistance and adopts Aquos Akwimos as his Guardian Bakugan for *Gundalian Invaders*. During *Gundalian Invaders*, Marucho, now approximately sixteen, utilizes Akwimos. He collaborates with Ren Krawler to create and manage Bakugan Interspace, a global virtual battling platform where he achieves the #3 rank. He demonstrates strategic brilliance in the Gundalian-Neathian war, devising military tactics and earning recognition as a "gift to Neathia" from Queen Serena. He struggles emotionally with Ren's betrayal but ultimately helps redeem him, participating in key battles against Gundalian forces like Stoica, Gill, and Airzel. In *Mechtanium Surge*, Marucho operates Bakugan Interspace, now an open-source system managed by an automated computer. He primarily uses Aquos Infinity Trister in the first arc, later switching to Aquos Radizen (with temporary use of Subterra Roxtor) in the second arc, adopting a dual-attribute strategy. He faces challenges maintaining Interspace's stability as chaos escalates due to infiltration by antagonist Mag Mel using Team Anubias and Team Sellon. Following intensified Chaos Bakugan attacks orchestrated by Mag Mel, Marucho initiates the deletion of Bakugan Interspace to contain the threat, a necessary but life-risking decision. His relationship with his father, Kyosuke Marukura, resurfaces when Kyosuke pressures him to quit the Battle Brawlers and assume responsibilities within the Marukura Group corporation. Despite initial apprehension, Marucho reaffirms his commitment after winning a significant battle. Kyosuke eventually accepts this choice with pride and later provides technical assistance, helping locate Interspace access points and participating in the deletion protocol. Marucho acts as a mediator during team conflicts, notably between Dan Kuso and Shun Kazami regarding Drago's uncontrollable powers. He consistently provides tactical support during battles against threats like the rogue Mechtogan Zenthon and Mag Mel's forces, remaining integral to the team's efforts to protect Earth and New Vestroia.