Fumio Fukamachi, father of Sho Fukamachi, became a widower when his wife died as Sho turned three. Her death remained unrelated to Chronos Corporation conflicts. Fumio worked diligently as a salaryman, devoted to supporting his son through their shared grief. Their relationship thrived on mutual care, with Sho avoiding burdens to spare his father further pain. Chronos abducted Fumio, imprisoning him at their Mount Minakami facility. Under Dr. Barcas, he endured involuntary Zoanoid processing that transformed him into Enzyme II—a hyper-zoanoid engineered to destroy Guyver armor. This form granted corrosive abilities to dissolve bio-boosted armor, clawed tentacles, and enhanced physical traits. Barcas perfected the transformation and maintained telepathic dominance, confining Fumio until Sho infiltrated the base to rescue him. Unaware of his father's condition, Sho led Fumio to safety. Outside, Barcas remotely activated the Enzyme II transformation, compelling Fumio to attack Sho violently. Controlled by telepathy, Fumio crushed the Guyver's head and tore out part of its brain module, nearly killing Sho. Recognizing his father, Sho refused lethal retaliation. The Guyver unit, operating autonomously as Sho faltered, severed Enzyme II’s arm and tentacle before annihilating it with a point-blank Mega-Smasher. As the beam struck, Fumio regained momentary awareness, screamed Sho’s name, and died instantly. This trauma repressed Sho’s memories and bio-boosting ability until a clash with the renegade Zoanoid Aptom restored both, allowing Sho to reconcile with his father’s fate. Fumio’s narrative role centers on catalyzing Sho’s psychological growth, with his background and personality explored solely through his bond with Sho and his transformation.