Yoriko Shikura, a housewife working part-time as a supermarket cashier, feels that she is not truly needed by anyone—neither her supermarket manager and colleagues, nor her husband and children.
One day, Yoriko is forced to stay late to check the inventory of frozen foods inside a large walk-in freezer. While she is doing the inventory, an employee fails to notice she is inside and locks the door, trapping her in the freezer.
She tries to contact a security guard using the intercom, but he is too busy chatting with another worker to notice her SOS. With no other choice, she wraps herself in a makeshift coat made of cardboard and decides to wait for rescue. Will she freeze to death in here? She manages to keep herself slightly warm with the flame of a small lighter, but it is a drop in the bucket inside a freezer designed to maintain sub-zero temperatures. As her consciousness fades, she worries about her beloved son…
When she comes to, she wakes up in a hospital bed. It seems she was rescued from that freezer just in the nick of time. However, starting that very day, Yoriko notices something strange about her body.
In the scorching heat, she asks her husband for a hot drink, yet she feels her son's hand—which he pulls to invite her to play—as ice-cold. Furthermore, when she is in charge of a food tasting booth at the store and accidentally places her palm on a hot iron plate used for grilling meat, she feels no heat at all. She visits a doctor to have her abnormal body examined, but nothing is found, and she is simply told that trauma from being trapped in the freezer must be lingering in her mind.
One day, when her family takes on a challenge course to finish a piping-hot dish together, she easily polishes it off, astonishing the restaurant owner. Her tongue has forgotten not only burns, but even the very sensation of "hot."
From then on, her bizarre "sensitivity to cold" knows no bounds. On midsummer days with shimmering heat waves, she wears heavy layers of winter clothes, drawing strange looks from those around her. She plunges her bare hand into boiling water to heat up a tasting retort pouch. During a work break, when a colleague hands her a cup of hot tea, she picks a fight, complaining, "It's cold. Don't serve me frozen tea." Eventually, she lines up heating appliances all around her room, wraps herself in blankets like a bagworm, and finds it difficult even to go outside. When she hugs her son, who worries about her, she instinctively pushes him away because of how freezing cold she is. Her son gently reassures her, saying, "I'm okay," but her husband finally flies into a rage over her drastic transformation.
Unable to hug her son and despairing that her husband no longer loves her, the protagonist eventually decides to commit suicide by jumping off the roof of a building. Just then, she hears sirens echoing from the town. Rushing over, she sees that a fire has broken out in an apartment building, and a child is left behind inside. Thinking that she is going to die anyway, she plunges into the flames in an act of self-sacrifice. Her body, which no longer feels "heat," easily rescues the boy, and she is thanked by the child's mother and the firefighters.
There, Yoriko finds her "reason for living." Originally, her parents gave her the precious name "Yoriko" out of the wish that she would "become a child whom someone can rely on." Realizing this, and determined not to shame that name, she studies frantically and officially joins the fire department. Today, a fire has broken out somewhere, and she rushes to the scene. "Hey! There's someone inside!" Hearing what sounds like a fellow firefighter's voice, she heads in for the rescue. Waving to her husband and son, who are cheering for her brave figure from among the onlookers, she leaps into the raging inferno…
The scene shifts. Back inside the freezer where Yoriko was trapped. "Hey! There's someone inside!" When the rescue team rushes in, Yoriko's lifeless body is found there, her hair and skin turned white with frost.