Heavy Object is a science fiction anime that takes place in a future where warfare has been transformed by the deployment of massive, spherical tanks called Objects. These Objects, which are virtually impervious to traditional weaponry and possess immense destructive power, have become the deciding factor in battles. The 37th Mobile Maintenance Battalion of the Legitimate Kingdom, comprising students like Qwenthur Barbotage, a novice Object designer, and Havia Winchell, a radar analyst from a noble family, operates alongside their Object, the Baby Magnum, piloted by Milinda Brantini. As they fight in various global battles, the battalion faces numerous impossible situations where Objects are the primary adversaries.