Sen is one of the novel’s two protagonists, a young female samurai whose 19th-century narrative runs parallel to Lee’s. As a dynamic and round character, her arc is defined by a tragic struggle between filial duty and self-preservation. Sen’s primary motivation is her desperate need for her father’s approval, a force that compels her to endure brutal training and commit horrific acts. Raised to believe “The sword is the soul of the samurai” (224), she views mastery of the blade as the sole path to earning her father’s love and respect. This intense desire for validation makes her a willing instrument of his cruelty, leading her to participate in the mutilation of her own mother and the execution of a captured spy. Her identity is so completely subsumed by her father’s expectations that she is willing to sacrifice her own morality and, ultimately, her life for him, declaring, “I would rather die for my father than live for you” (274).

To cope with the cognitive dissonance between the honorable warrior she idealizes and the cowardly man her father has become, Sen develops a protective delusion. She convinces herself that the man who returned from the failed Satsuma Rebellion is an imposter who has taken her “true” father’s place. This psychological defense mechanism allows her to preserve the myth of her father’s honor while still obeying the commands of the cruel man who now leads her family. This coping strategy mirrors Lee’s invention of a false reality, connecting both protagonists through their shared experience that enables them to process unbearable truths. Her delusion emphasizes her deep investment in The Destructive Myth of Samurai Honor, as she cannot accept that the code her entire life is built upon could be a facade for cowardice and shame.

Sen’s interactions with Lee catalyze her transformation from an overly obedient daughter to an individual who asserts her own will. Lee’s world, a future where the samurai are nothing but a historical curiosity, forces her to confront the futility of her father’s cause. While initially hostile, she develops a deep connection with Lee, recognizing him as a fellow lonely soul trapped by family trauma. This relationship gives her a glimpse of a life beyond her father’s control. In the novel’s climax, her father commands her to kill Lee. In a final, powerful act of defiance, Sen refuses, choosing to protect Lee and herself over her lifelong duty. She declares that her true father died in the rebellion and that she has chosen herself. This assertion of her own identity is both her greatest triumph and the direct cause of her death, completing her tragic arc from a weapon of her father’s will to a person in her own right.

Iwasaki Itaro, Sen’s father, serves as the primary antagonist in the 19th-century timeline. He is a static, round character who embodies the novel’s critique of samurai ideals, functioning as a deconstruction of the honorable warrior archetype. His character is driven by a deep and festering shame stemming from his actions during the Satsuma Rebellion. Instead of dying in battle or dying by suicide via seppuku, he fled, an act of cowardice that contradicts the very code of honor he espouses. To cope with this dishonor, he becomes a tyrant, using quotations from the samurai text Hagakure to justify horrific domestic abuse and to force his family into a fanatical, isolated existence. He manipulates Sen’s desire for approval, forging her into a weapon to carry out his cruelties, such as forcing her to mutilate her mother for speaking out against his authority.

Itaro’s ultimate motivation is to erase his past cowardice through a final, violent act that he can frame as honorable. Knowing the imperial government is hunting him, he refuses to flee, choosing instead to orchestrate his death in the misguided belief that it will preserve his honor. His murder of his wife and sons, and his attempt to force Sen to be his kaishakunin (his ritual assistant), are acts of a desperate man attempting to escape capture and rewrite his legacy. Through Itaro’s character, the novel argues that the destructive myth of samurai honor is a hollow facade used to mask deep fear, cruelty, and selfish pride. His actions are the direct cause of his family’s destruction, revealing the rot at the core of the ideals he claims to uphold.

Hina appears as a compassionate and enigmatic figure, acting as Lee’s father’s girlfriend and a gentle guide for Lee himself. However, her true identity is Otohime, the sea goddess from the Urashima Tarō folktale, making her a supernatural trickster and mentor figure. In the 19th century, she appears as Youna, a kind maid who offers Sen comfort. As Otohime, she is the architect of the novel’s central conceit, having created the house as a temporal sanctuary to protect both Lee and Sen from the unbearable trauma of their real deaths.

Otohime’s motivation stems from a deep sense of loneliness and a desire to spare her “children,” Lee and Sen, from their painful fates. Having experienced the loss of a human she once cared for (Urashima Tarō), she creates repeating time loops within the house, allowing Lee and Sen to exist in fabricated realities where the sources of their trauma are suppressed. She manipulates events to bring them together, sensing their shared loneliness and hoping their connection might offer them solace. The sea and turtles are her symbols, representing her control over time and the false refuge she has built. While her intentions appear benevolent, her actions ultimately trap the protagonists in a cycle of delusion and violence, preventing them from confronting the truth and achieving any real resolution.