Military officer Zelbert (also identified as ZellBerd or Zellberg) served under Hell Deathbird, commander of the Ocean Empire's forces. His allegiance fractured when Deathbird destroyed the Empire's underwater colony, an act Zelbert deemed an unforgivable atrocity. This betrayal drove Zelbert to defect and attempt a coup against Deathbird, aiming to overthrow the commander's tyrannical rule by aligning with the protagonists. The rebellion failed, culminating in Zelbert's death during the confrontation.