Hōshimaru is not allowed to enter the battlefield but observes the castle’s women cleaning and dressing the severed heads of the enemy samurai who have been killed.
He wishes to repeat the excitement, and secretly enters the enemy camp so he can claim a head and bring it back to the girl and make her smile again.
The purpose of the marriage is to reconcile the two families; however, Lady Kikyō wants to avenge her father’s humiliating but secret death and arranges for her husband to be attacked by bow and arrow in order to sever his nose.
Two attacks narrowly fail: in the first Norishige is injured with an arrow in his upper lip, disfiguring him and severely affecting his speech; and in the second he loses an ear.
Terakatsu succeeds his father as Lord of Musashi and attacks Norishige’s castle, intending to take his possessions and his wife.
She rejects Terakatsu, who subsequently “sought out new women, one after another, with whom to share his bizarre stimulus and revolting dissipation.” The Secret History of the Lord of Musashi was one of several of Tanizaki’s works in “essay-fiction” between 1930 and 1950, combining experimentation and tradition, including Mōmoku Monogatari (A Blind Man's Tale, 1931), Ashikari (The Reed Cutter, 1932), Shunkinsho (A Portrait of Shunkin, 1933), and Shōshō Shigemoto no haha (Captain Shigemoto's Mother, 1949–1950).
The narrative technique of The Secret History may have been inspired by Stendhal’s The Abbess of Castro, which Tanizaki translated into Japanese in 1928.
Tanizaki had originally planned to write a long historical novel and expressed a desire to include a portrayal of a real individual woman rather than one of the anonymous figures in traditional literature.