A young mother Keiko and her four children move into a cramped Tokyo apartment where only the eldest, Akira Yûya Yagira, is known to the landlord. Akira helps bring his younger siblings, Shigeru Momoko Shimizu and Yuki Hiei Kimura, into the unit inside suitcases, while the elder sister Kyōko Ayu Kitaura arrives separately by train. Each child has a different father, and Keiko forbids schooling or contact with outsiders, keeping Akira as the only one allowed to venture outside. The setup is stark and fragile, with the family clinging to a sense of togetherness in a place that feels more like a shelter than a home.
After a few months, Keiko reveals she has a new boyfriend and hints that the children might eventually lead normal lives if she marries, though Akira is visibly doubtful. Without warning, Keiko disappears for months, leaving only a small amount of money behind. Akira steps into a managerial role, paying the rent and tending to his younger siblings, often from a position of improvisation and improvising dignity in a bedro-bed-roof world. When money runs thin, Akira turns to men who might be Yuki’s biological father, asking for help, navigating a maze of promises and disappointment.
Keiko eventually returns, bringing gifts for the children, but she soon leaves again, promising to come back for Christmas and never returning. The seasons change—from Christmas to New Year to spring—without her return, and Akira and Kyōko are forced to become surrogate parents. Akira discovers evidence that she has married and left them forever, though he keeps that truth from his siblings, choosing to shield them from further hurt. As funds dry up, they subsist on inexpensive store food, and the apartment grows quieter and more neglected.
On Yuki’s birthday, she asks to go outside to wait for their mother at the train station. The siblings seize the chance for a rare day of freedom and a simple outing, and Akira promises Yuki that one day he will take her on the Tokyo Monorail to see the airplanes take off at Haneda Airport. In time, Akira befriends two boys his own age who begin to visit the apartment, bringing games and roughhousing into their world. The presence of these visitors both livens and strains the family’s fragile routine, and Akira starts to neglect his siblings as responsibilities pile up.
The apartment itself begins to crumble: electricity, gas, and water are turned off, and the children wash in the park’s public toilets and use the tap there for water. During one of these park trips, Shigeru forms a tentative friendship with Saki, a high school student who cuts class. Saki starts visiting regularly and helps with care, sometimes offering financial assistance that Akira politely refuses, wary of taking help that might entangle the family in trouble enjo kōsai.
As summer looms, money remains tight and weariness grows heavy on the siblings. Akira plays baseball when a junior high coach needs an extra player, a momentary escape from their routine. While he is away, Yuki falls from a stool while reaching for something, and the loss hits hard. Grieving, Akira reconsiders Saki’s support and, with her help, buys multiple boxes of Yuki’s favorite chocolate candies. They place the chocolates with Yuki’s body in a suitcase and carry it to a field by Haneda Airport’s runway. There, they dig a grave and bury the suitcase—an act that brings a sense of closure, even as the family returns to the apartment and continues with their precarious life.
The film closes with Akira, Kyōko, Shigeru, and Saki walking home together. Saki’s hair is tied in pigtails, evoking Yuki’s own unmistakable style, a small, poignant reminder of what they endured and what they chose to carry forward. Through quiet, unsentimental detail and restrained emotion, the story traces a family’s stubborn, resilient bond in the face of abandonment, poverty, and the everyday decisions that keep a group of siblings together when the world seems determined to pull them apart.
