"Roujin Z" is set in early 21st century Japan. A group of scientists and hospital administrators, under the direction of the Ministry of Public Welfare, have developed the Z-001: a computerized Home automation for the elderly and disabled. The Z-001 takes complete care of the patient: it can dispense food and medicine, remove excretory waste, bathe and exercise the patient lying within its frame. The bed is driven by its own built-in nuclear power reactor—and in the event of an atomic meltdown, the bed (including the patient lying within) would become automatically sealed in concrete. The first patient to be "volunteered" to test the bed is an 87 year-old dying widower named Kiyuro Takazawa. He is an invalid who is cared for by a young nursing student named Haruko. The electronic elements within the Z-001 somehow manage to transcribe Takazawa's thoughts through Haruko's office computer, and he uses the communication to cry for help. Although she objects to such treatment of elderly patients, Haruko begrudgingly seeks the aid of a group of computer hackers in the hospital's geriatrics ward to create and install a vocal simulation of Takazawa's deceased wife in the Z-001. However, once Takazawa wishes to go to the beach, the Z-001 detaches itself from its moorings and escapes from the hospital with the man in its grasp. Haruko's fears are then justified, as it is discovered that the bed is actually a government-designed, experimental weapons robot.