Subjectivity
The theme of subjectivity is most notably expressed through the story's unconventional structure. In place of an objective third-person authorial presence, Akutagawa chooses to convey the events of "In a Grove" through individual testimonies and confessions, each of which are inherently limited by subjective perspectives. Subjectivity becomes increasingly relevant as the story progresses and the reader is exposed to contradictory information. Each character's account sounds reliable and is consistent within its own logic, but when read together, the accounts create a knot of discrepancies that the reader cannot untangle. Without an objective perspective on the story, the reader only has subjective perspectives, none of which can be proved any more true or false than any other.
Contradiction
A thematic insistence on contradiction is perhaps the most pervasive and perplexing element of "In a Grove." Just as the reader begins to develop a clear picture of the events that occurred in the bamboo grove, the second half of the story presents contradictory information that undermines any possibility of clarity. Even what we have been told about characters early in the story, such as Masasgo's mother saying Takehiro is kind, are contradicted in the latter half, such as when Takehiro stares at Masago with cold contempt. While potentially frustrating, the opposition and inconsistency is ultimately in service of grand thematic resonance. The story illustrates that the impossibility of discerning truth from contradictory perspectives may itself be the most profound truth about life.
Honor
Though Akutagawa does not explicitly mention honor in "In a Grove," the three major characters convey through their decisions and attitudes that there are particular codes of honor they abide by. After she is raped, Masago—who had only been with Takehiro until then—believes it right that she and Takehiro should die together, as though it is not possible for them to live on in their dishonorable state. Similarly, Takehiro, despite being freed by the bandit at the end of his testimony, kills himself without hesitation—a fitting end for a samurai. Even Tajōmaru conforms to conduct that matches the perverse honor of a bandit. When it is time to kill Takehiro, he gives him the option of a duel. And when captured, Tajōmaru accepts his punishment and asks to be executed, a fate he had always anticipated and is perhaps relieved to have met. Though Takehiro, Masago, and Tajōmaru have their own ideas of honor, it is interesting to note that they each expect or seek their own death as the logical repercussion of the story's events.
Death and Rebirth
The cycle of death and rebirth is a theme first touched on when the priest compares Takehiro's life to a drop of dew and a flash of lightning—natural phenomena that existent only for an instant, but are guaranteed to reemerge again in another form. At the end of the story, Takehiro's spirit has sunk into "the darkness that exists between lives," a figurative means of stating that he has not reached Buddhist enlightenment and is still trapped in the cycle of rebirth, awaiting entry into his next life. The bamboo grove itself carries a parallel symbolic resonance, since it is an empty form in which the truth of the universe can be contained; to achieve such emptiness in oneself is the only way for a being to reach Buddhist enlightenment and be freed from the cycle of rebirth.
