Marucho Marukura, also known as Chōji Marukura, hails from a wealthy family as an only son, initially displaying extreme obedience toward his parents out of fear. This dynamic transformed after he joined the Battle Brawlers, though he retained respect for his family and later reconciled with his past as integral to his identity. As a core member across all seasons, he commands the Aquos attribute and functions as the team’s chief strategist, employing analytical prowess and encyclopedic Bakugan knowledge to craft combat tactics. His original guardian, Aquos Preyas, joined him after crashing a housewarming party in Dan Kuso’s town. Preyas evolved into Angelo/Diablo Preyas during a clash against Klaus von Hertzon, gaining a unique split-entity ability while preserving its core form. Temporarily lost to the Doom Dimension, Preyas was recovered through a joint effort by Dan Kuso and Runo Misaki.

In New Vestroia, Marucho accompanied Dan and Drago to support the resistance against Vestal occupation, initially lacking an Aquos partner after Preyas’ capture. He later bonded with Elfin—an Aquos Bakugan trained by Preyas—after proving his mettle in a collaborative skirmish against Vexos member Mylene Farrow. Adopting new attire, he aided in dismantling the Vestals’ Dimensional Controllers. A psychological trial orchestrated by Frosch forced him to confront his former submissive self, cementing his acceptance of personal growth and transition into a more assertive role. He participated in New Vestroia’s liberation and returned to Earth following King Zenoheld’s defeat.

During Gundalian Invaders, Marucho—now approximately 16—relocated to Bayview and became administrator of Bakugan Interspace, a global virtual battling platform he engineered using Phantom Data from Ren Krawler. His technological ingenuity enabled user digitization for interspace access, though this innovation drew malicious entities attempting to hijack the system. He transitioned to new guardians: Aquos Akwimos and later Aquos Trister (or Tristar), the latter sourced from Gundalia. Trister proved vital in stabilizing Bakugan Interspace during disruptions triggered by Dan’s Bakugan Drago and combated external threats like the rogue Mechtogan Zenthon.

In Mechtanium Surge, Marucho continued overseeing Bakugan Interspace while adopting a dual-attribute strategy with Aquos and Subterra Bakugan. He supported the team against Mag Mel and Razenoid, including efforts to prevent Bakugan City’s annihilation by Mechtavius Destroyer. His arc highlights adaptability—evolving from a data-reliant tactician to a leader balancing strategy with real-time decisions—while consistently serving as the team’s benefactor and moral anchor.