Commander Sugata discovered the existence of the Royal Underground Empire Tube, a malignant force that desires to dominate the land, which is based underneath Japan. He recruits five young people, each one specializing in a style of martial arts, and teaches them in the ways of the mystical "Aura Power" energy. A year after he recruited and trained the Maskmen, Tube is ready to strike.

Adachi's follow-up to Bowl using the figure of a woman suffering from an unusual sexual aliment has often been taken as a controversial allegory for the political stalemate of the Leftist student movement after their impressive wave of massive fiery protests failed to defeat the neo-imperialist Japan-US Security Treaty. The ritualistic solemnity of the charged sexual scenes contribute to the oneiric qualities of Closed Vagina which Adachi would later insist was an open work, not meant to deliver any kind of deliberate political message. - Harvard Film Archive