I always knew my head would end up hanging in the tree outside the prison (Situational Irony)
Though the image of prisoners hanging from the tree outside the prison would be seen by most people as forewarning not to commit crimes, the bandit Tajōmaru understands this to have been his fate. Tajōmaru’s request to be killed and displayed is an ironic reversal of a person's natural fear of death: he is resigned to the fact that his head will end up hanging in the tree, which suggests that he is perhaps relieved to have reached the inevitable end of his life.
Takehiro’s look of contempt (Situational Irony)
After Takehiro witnesses Masago being raped, a reader would expect him to be sympathetic to his wife. However, Masago says that Takehiro looked upon her with contempt in his eyes, as though she were somehow responsible. In this ironic reversal of expectations, Masago then decides she must kill him and herself as the only reasonable response to the shame she feels.
Masago’s betrayal (Situational Irony)
Takehiro’s testimony refutes the accounts given by both Masago and Tajōmaru when he claims that Masago decided not only to go off with the bandit but insisted he kill her husband. This detail introduces an incongruity between Masago’s self-characterization as devoted and honorable, and Takehiro’s characterization of her as having betrayed him. The situation is ironic because it subverts the reader’s understanding of not only what took place but whether anyone’s account of reality can be trusted.
