In the distant future, the nature of war has shifted. "Objects"—massive, spherical tanks that are impervious to standard weaponry and equipped with devastating firepower—dominate the battlefield; their mere presence guarantees victory, making conventional armies obsolete. Yet, this new paradigm of warfare is on the verge of being overturned. Qwenthur Barbotage, a student of Object Design, and Havia Winchell, a radar analyst of noble lineage, serve in the Legitimate Kingdom's 37th Mobile Maintenance Battalion. Their duty is to support the Baby Magnum, one of the nation's Objects. Tragically, a battle gone wrong leaves the pair in a desperate predicament: ordinary infantry are forced to confront the overwhelming power of an enemy Object. As they struggle to save themselves and their comrades, a spark of hope emerges, forever altering the world's understanding of Objects. Heavy Object tracks these two soldiers, along with Milinda Brantini, the pilot of the Baby Magnum, and their commanding officer, Frolaytia Capistrano, as the unit travels across the globe to engage in battle after battle. Confronted with one impossible scenario after another, they must rely on all their wit and courage to defeat the seemingly insurmountable foes that are the Objects.