In 1961 Yukio Mishima published a short story, "Patriotism" (Yukoku), the first of several works devoted to the ideals of the rebellious young officers of the 1930s. As his admiration grew into emulation, he himself began training with the Self-Defense Forces, and by 1968 he had formed his own private 100-man army, the Tate no Kai (Shield Society). He had further plans, and these were indicated early on when he decided to turn "Patriotism" into a short film.
In the spring of 1965 he was at Okura Studios, himself playing the idealistic young officer who bids farewell to his wife (Toshiko Tsuruoka) before they kill themselves. Her death is discreet, a small dagger, but his is spectacular -- full hara-kiri with lots of blood and intestines.
The filming was completed in just two days. Technicians had been borrowed from Daiei and this was the amount of time they could spare from their schedules. At Mishima's insistence, all of this was kept secret and the names of these assistants do not appear on credits of the film.