In the bustling Shibuya ward of Tokyo, Hirayama diligently serves as a public toilet cleaner, showcasing an unwavering commitment to his work that highlights his meticulous nature. His home, situated across the Sumida River, feels worlds apart from the vibrant district he tends to daily. Rising with the dawn, Hirayama embarks on a structured routine that includes indulging in his love for music cassettes while commuting in his van. His literary tastes lean towards the works of noted authors like William Faulkner and Patricia Highsmith, alongside philosophical essays by Aya Kōda, providing him solace through their profound insights. As twilight descends, Hirayama's dreams unfold like impressionistic images, hinting at the depth of his inner struggles.
In his spare moments, Hirayama finds joy in nurturing his cherished trees, capturing the ephemeral beauty of komorebi (木漏れ日) — the delicate interplay of sunlight filtering through leaves — with his camera. His respect for nature's artistry is apparent in the careful attention he gives to these living masterpieces. Conversely, his assistant, Takashi, often disrupts the tranquility of their environment with his tardiness and boisterous demeanor, much to Hirayama's annoyance. However, fate takes a turn when Takashi encounters a young woman named Aya at their workplace, setting off a chain of events that profoundly affect Hirayama's life.
The recklessness of Takashi's lateness leads him to rush through his tasks, prompting him to borrow Hirayama's van in a moment of desperation. Unbeknownst to him, this act will trigger repercussions that neither he nor Hirayama could foresee. After realizing the worth of Hirayama's treasured music cassettes, Takashi attempts to persuade his boss to part with them, only to be met with resolute refusal. As time trudges on, Hirayama finds himself at a crucial juncture, contemplating the true nature of his life and the choices he faces.
Amid these turbulent changes, Hirayama engages in a spontaneous game of tic-tac-toe with a stranger, each move revealing strategies that echo the unpredictability of life. In these moments of quiet introspection, he steals glances at a mysterious woman who seems to symbolize the deeper possibilities of existence, hinting at a life beyond his well-ordered daily routine. When Aya returns Hirayama's Patti Smith cassette, she requests one last ride in his van, her gentle kiss on his cheek leaving him visibly unsettled. Following this interaction, Hirayama immerses himself in self-care, dedicating time to laundry, film development, and new literary adventures. He even dines at a local eatery, where the warmhearted proprietor shares tantalizing gossip, providing a stark contrast to the turmoil brewing within him.
Out of the blue, Niko, Hirayama's niece, arrives at his doorstep, having fled from the lavish yet stifling surroundings of her estranged mother, Keiko. Graciously, Hirayama welcomes Niko, introducing her to the beauty of their surroundings by taking her to work with him. Together, they share joy-filled moments capturing the park's arboreal splendor and riding bicycles — experiences that strengthen their familial bond.
However, the fleeting joy is soon overshadowed when Keiko arrives in a luxurious car, her sorrowful demeanor signaling the gravity of her visit: their father's condition has tragically declined due to dementia, stripping him of the ability to recognize those he once loved. This revelation devastates Hirayama, his heartbreak spilling forth in a torrent of tears, rendering him vulnerable.
The difficulties compound when Takashi abruptly resigns, leaving Hirayama to shoulder the burden amidst his already fragile emotional state. Seeking solace in familiar surroundings, he visits his favorite restaurant, only to stumble upon a heartbreaking reality — the proprietor reconnecting with a man she hasn't seen in years. Overwhelmed, Hirayama retreats, seeking refuge by the riverbank with cigarettes and canned drinks in hand.
In a moment of serendipity, Hirayama encounters a stranger who shares his cigarette, unfolding a conversation that reveals the truth about the restaurant's owner: she is his ex-wife. The man implores Hirayama to take care of her as he faces his own cancer diagnosis, a conversation that imbues Hirayama with a fleeting sense of purpose as they part ways.
As dawn breaks on a new workweek, Hirayama is greeted by the soothing sounds of Nina Simone's Feeling Good, a balm for his troubled heart. Driving through the city's streets, the conflict of emotions — grief, sorrow, and regret — plays across his face, highlighting the profound reckoning that awaits him. It becomes undeniable that Hirayama's world stands on the brink of transformation, compelling him to confront the core of his human experience.
