Daru is the central character and narrator of the story, a male black cat who shares a small apartment with his owner, a young woman named Miyu. His life is presented from his own feline perspective, offering a quiet and intimate view of the human world he inhabits.

As a kitten, Daru was found and brought home by Miyu's mother, a beginning that was not immediately warm. Miyu was initially cold and distant towards him, a period marked by small disasters like a broken favorite cup and the unsettling gift of a dead lizard, which is a cat's natural expression of affection. This early friction, however, slowly gave way to a deep and abiding bond as they grew up together, making him a constant presence through the significant changes in her life from childhood to college.

Daru possesses a personality that is observant, contemplative, and deeply affectionate. He is not overly anthropomorphized; while he narrates his thoughts, his behavior and understanding remain authentically feline. He cannot understand the specific words Miyu says, but he is highly attuned to her tone of voice, her actions, and her emotional state, confidently believing that their thoughts are often the same because of their close connection. His narration reflects a profound love for his owner, whom he sees as an unwaveringly kind and beautiful person, even as he witnesses her struggles with loneliness, job interviews, and the pressure of modern life. He sees past her moments of despair to appreciate her quiet determination, and his affection is the lens through which the entire story is told.

Daru's core motivation is simple but absolute: the well-being and happiness of his owner, Miyu. He feels a sense of helplessness at being unable to actively solve her problems, such as her financial troubles and her strained relationship with her own mother, but his presence is a constant, silent source of comfort. His role in the story is that of a devoted witness and companion, whose love ultimately drives the narrative's most significant turning point. Sensing that his own life is nearing its end and seeing Miyu's continued unhappiness, he performs one final, extraordinary act: he deliberately knocks over her phone, successfully dialing her mother's number and forcing a reconciliation between them. Having found a way to bring her happiness one last time, he then peacefully passes away in her arms.

Throughout the series, Daru shows signs of aging, which adds a poignant layer to his character. He begins to sleep more, his memories become cloudy, and he reflects on his own finite existence as he watches the seasons change. This development leads to his final, selfless act, completing his journey from a disruptive kitten to a wise and comforting, if aged, companion. One of his most notable abilities is his perceptive emotional intelligence; he acts as a sponge for Miyu's pain and loneliness, offering silent comfort that is mutually beneficial. His final clever action with the telephone is presented as an extraordinary feat driven by instinct and love, highlighting the deep, almost mystical, connection between them. After his death, the story hints at a cycle of connection, as Miyu later finds a stray white kitten whose narration suggests a faint, lingering sense of familiarity with her scent, implying a reunion of their souls.