Mitsukuni Hyuga, 54, is the black-haired founder and CEO of Tokyo's Hyuga Corporation. Headquartered in Gaien-mae, his company rapidly grew by commercializing artificial muscle fiber technology to enhance human physical capabilities. As a strict corporate leader, he disciplined his son, Kotaro Hyuga, from childhood to prepare him for succession, ultimately appointing Kotaro project leader for the company's powered suit development.

Mitsukuni's driving ambition centers on completing the Marishi Machina, a powered suit designed to grant average individuals elite athletic prowess. This project is a strategic bid for market dominance and industry monopoly. He disclosed to employee Dan Amo the possibility that Dan's mother might still be alive, prompting Dan and journalist Makina Mikage—who seeks answers about her missing father—to visit Hyuga Corporation's secret Mount Fuji testing facility. There, Mitsukuni connected both their parents to the original Marishi Machina development team. He proposed that restarting the same test conducted years ago could help Dan revive his mother from cryogenic suspension and reveal her father's true objectives to Makina.

After Makina lost consciousness during a test where the suit seized control of her body, Mitsukuni intercepted Dan and Makina on their return. Confronted by Makina about the incident that caused their parents' deaths, he issued an unexpected order to Dan, his expressions noted as unsettling.