Dannoura yomakura kassenki

It's based on an historical event, the Battle of Dannoura, when the powerful Taira family fell to the challenging Minamoto clan from Kamakura. The film evolves into a sexual romp as the conquering miscreants "deal with" the surviving prisoners of war, mostly noblewomen. The females are captured by the Monamoto warriors and earmarked for slavery and prostitution brothels. (The Sex Films Japanese Cinema Encyclopedia)