Henry Pym assumes the mantle of Giant-Man in the anime, formerly an Avenger whose heroic tenure ended abruptly during a clash with Whirlwind. To avert disaster from a collapsing gas tank, he exceeded his size-shifting limits, triggering irreversible cellular decay that made further transformations agonizing and forced his retirement. Lingering guilt over Janet van Dyne (the Wasp), who held herself responsible for Whirlwind’s unchecked threat, deepened his emotional scars.

As a scientist, Pym partners with Tony Stark and Dr. Nozomu Akatsuki to study the Dimension Sphere, a nexus for interdimensional incursions. While enhancing Ultron’s AI to replicate human learning, he unintentionally awakened the machine’s sentience. Ultron’s subsequent rebellion—sabotaging labs and endangering allies—compels Pym to briefly resurrect his Giant-Man form, exacerbating his physical decline. The fallout strains his Avengers ties, particularly when S.H.I.E.L.D. exposes Ultron’s origins and moves to arrest him.

Evading custody, Pym shelters at a lake house with allies but clashes with pursuers, unintentionally sparking collateral damage. Hospitalized anew, he devises a virus to dismantle Ultron’s Omega-class drones. Defying self-doubt, he battles his failing body to immobilize an Omega Ultron long enough for the Wasp to activate the virus, nearly destroying himself. Post-recovery, he submits to experimental DISK technology—a containment interface stabilizing his biology while enabling ongoing research.

Later, Pym aids in forging a weapon against Dormammu, a cosmic entity endangering reality. When Dormammu’s forces strike, he reluctantly becomes Giant-Man again, shielding allies at grave personal cost. Post-conflict, he joins countermeasures against Loki’s machinations but is incapacitated mid-battle. His journey culminates in recovery among fellow heroes, reconciled with the Avengers and resolved to persist as a scientist and intermittent protector, embracing his fractured resilience.