In Tokyo, a teenage girl named Gorgeous, Kimiko Ikegami, so celebrated for her beauty that everyone calls her by that nickname, has a carefree plan for a summer vacation with her widowed father, a wealthy film composer who has spent months abroad in Italy. When he returns home, he drops a bombshell: he has married a woman named Ryoko Ema, Haruko Wanibuchi. Crushed and unsettled, Gorgeous retreats to her room and pens a letter to her aunt, begging to spend the summer with her instead. Her plea is granted, and she gathers six close friends who will accompany her on this rural retreat: Prof, Ai Matsubara a prodigy of problem-solving; Melody, Eriko Tanaka with a natural affinity for music; Kung Fu, Miki Jinbo a fearless athlete skilled in kung fu; Mac, Mieko Satoh whose appetite is legendary; Sweet, Masayo Miyako a bubbly and gentle spirit; and Fantasy, Kumiko Ohba whose head is always in the clouds.
On arrival at the aunt’s countryside home, the girls are warmly greeted and—as a playful gesture—present a watermelon to their host. They tuck the fruit away in a well to keep it cold and begin to settle in. But the trip takes a dark turn when Mac goes to fetch the fruit and disappears. Later, when Fantasy checks the well, she discovers Mac’s disembodied head, which suddenly erupts and bites Fantasy’s buttocks, sending everyone into a state of confusion and fear. At first, the incident is dismissed as a prank, yet the house begins to reveal many more eerie and inexplicable hazards.
Soon the house itself seems to come alive with malevolence. The girls are repeatedly menaced or possessed by household objects: Gorgeous becomes possessed after peering into her aunt’s mirror; Kung Fu is assaulted by flaming logs, which scorch her clothes and threaten her safety; Sweet vanishes after a brutal encounter with a line of malignant mattresses. Desperate to escape, the girls attempt to flee, but Gorgeous finds a way out through a door while the others remain trapped inside.
Their search for the aunt leads them to a shocking discovery: Mac’s severed hand sits gleaming in a jar, an ominous reminder of the danger that surrounds them. Melody tries to lift the mood by playing the piano, and the others hear Gorgeous singing from upstairs, offering a brief glimmer of hope. But the piano turns deadly, biting off Melody’s fingers and ultimately consuming her life.
Upstairs, Prof and Kung Fu follow the sound of the singing to a scene where Gorgeous stands in a bridal gown, and the diary of her aunt becomes a chilling key to the mystery. Kung Fu trails after Gorgeous, only to stumble upon Sweet’s body entangled inside a grandfather clock, which bleeds in a terrifying display. The remaining three girls hastily barricade the upper floor and pore over the aunt’s diary, seeking any explanation or remedy.
Their reading is interrupted by a grotesque reveal: a giant version of Gorgeous appears, confessing that her aunt died waiting for a fiancé who never returned from World War II, and that the aunt now devours unmarried girls who come to the house. The trio is then assaulted by a cascade of household items that seem to have minds of their own. Prof shouts for Kung Fu to attack the aunt’s cat, Blanche, and an intense confrontation unfolds: Kung Fu makes a flying kick but is swallowed by a light fixture; her legs manage to escape, damage the cat’s portrait, and Blanche is killed, with the portrait spurting blood that floods the room. Prof is dragged underwater by a jar with teeth and dissolves. Fantasy witnesses Gorgeous in a bridal gown, paddling toward her, and in the reflection, Gorgeous shifts to resemble the aunt and gently cradles Fantasy.
When dawn breaks, Ryoko arrives again at the house, and finds Gorgeous dressed in a kimono. Gorgeous reassures her that the others will awaken soon and that they will be hungry, hinting at what has happened. She then raises her hand in a final, eerie gesture to Ryoko, who burns away to nothing, leaving the truth of the house’s horror to linger in the air.
