During the Second Sino-Japanese War, in 1940, Lieutenant Kurokawa returns home as a honored and decorated soldier but deprived of his arms and legs lost in battle. All hopes, from the villagers and women to close family members, turn to Shigeko, the Lieutenant's wife. She must honor the Emperor and the country in setting an example for all by fulfilling her duty and taking care of the 'god soldier'. Kurokawa prior to leaving to fight in the war regularly beat and berated his wife for her barrenness and inability to bring him a son. When he returns home as an amputee with no hearing and no speech, his wife dutifully attends to him, even though he shows little appreciation for her dedicated care. His main concerns are getting fed and getting sex. Even in his own degraded condition, he manages to berate his wife. Eventually, though, his own memories infiltrate and he is haunted by his horrible, sadistic deeds, performed while in the duty of the Japanese military.

Interspersed with archival footage relaying the origins of the political unrest of the 1960s, United Red Army introduces us to the young men and women who will ultimately become militant activists seeking to overthrow the established world order. Two of the most radical student groups form the United Red Army (URA) and head into the mountains to conduct a training camp. Ideology devolves into despotism, and the URA's leaders begin to arbitrarily persecute their followers, a harrowing ordeal that culminates in violence and murder.

Sparta Academy is the nation's top prep school, where students with poor grades undergo frightening torture under the school headmaster's direction. Kekko Kamen makes her appearance at the school in outrageous attire, completely naked except for her red mask, boots and gloves, and attacks the torturing teacher.