In the 1930s, Japan's civilian government was constantly under pressure from radicals in the military who wanted the military to have greater power and also wanted to use the military for imperialistic purposes. One of the more famous episodes in that continuing struggle was the 1936 mutiny.
"Patriotism" is set during that mutiny. Shinji Takeyama (I am putting the names in the first name first order that Westerners use) is a soldier whose unit is part of the mutiny. He has not been taken into their confidence and so is not part of it himself. However, he cannot bear the idea of attacking fellow soldiers whose ideals he shares.
Instead, Takeyama commits suicide, along with his wife Reiko. In doing so, he lives up to the ancient ideals of Bushido.