"Goddess of the Dark Tower" is based on Tenshu Monogatari, a play by Kyōka Izumi. It tells the story of a forbidden love between a god and a human. In medieval Japan, Zushonosuke Himekawa is a falconer who is sent by his master Lord Harima to retrieve a precious falcon named Kojiro. Zushonosuke's search is initially fruitless, though it leads him to a chance encounter with a beautiful woman bathing in a lake. Zushonosuke falls in love with her at first sight. When news reach Lord Harima that the falcon has in fact fled to the castle keep of Shirasagi-jo, Zushonosuke is ordered to go there to bring the falcon back. Accompanied by two friendly demons, Zushonosuke makes his way to Shirasagi-jo, which is rumored to be inhabited by beings called Wasuregami (Forgotten Gods). At the castle, Zushonosuke is surprised to find the same beautiful woman he encountered before, who introduces herself as Tomihime (Princess Tomi), beginning their forbidden romance.