Kotani receives a phone call from Narumi Hikizuri, a former underclassman whom he knew in junior high school. Narumi tells him that she is about to jump off a bridge near the boarding-house where Kotani lives. Kotani goes to the bridge and talks Narumi out of killing herself. She explains that she wants to die because she can't bear living with her brothers and sisters; the children in her family have been alone since their parents died several years ago. Kotani allows Narumi to stay with him for a while.
Narumi doesn't return for a week, and her siblings become impatient with her. Her eldest brother Kazuya is now the head of the family and takes care of the others: Kinako, Shigorou, Narumi, Hitoshi and Misako. Kazuya thinks Narumi is being selfish and trying to make him worry, and asks his siblings to help him find her. Meanwhile, Kotani is becoming fed up with Narumi, who is lazy, untidy and wastes his money. He tries to ask her to leave but she threatens suicide again, forcing him to allow her to stay. However, Shigorou sees Narumi on Kotani's balcony, and drags her back to the Hikizuri house. She is gone by the time Kotani arrives home.
Narumi is angry to have been brought back to her family, and insults her sisters when they criticize her actions. Kazuya decides that Kotani must be punished for seducing Narumi, and the others suggest various painful methods of murder and torture. When Hitoshi suggests that they simply ban him from seeing Narumi again, the siblings argue. Narumi announces that she can't take any more and is going to kill herself. She goes out to the garden, where she covers herself in kerosene and takes out a lighter. Despite Kazuya pleading with her to give him the lighter she sets herself on fire. Shigorou laughs as the others watch in horror.
Kotani misses Narumi even though he knows he should be relieved she's gone. Shigorou goes over to Kotani's house and tells him that Narumi is dead, having left a suicide note about how Kotani broke her heart. He insists Kotani come to the Hikizuri house to pay respects. The Hikizuris have placed Narumi's body on a futon, and pull back the blankets to show Kotani her charred corpse. They insist he atone for her death by spending the night on the futon with her. They force him onto the futon, accidentally knocking off Narumi's head. Kotani is horrified but the Hikizuris wrap him in the futon and roll him around, insisting he should suffer for what he's done. Kotani finally manages to get out of the futon, and runs through the house trying to escape. As he runs down a hallway, he sees Narumi standing at the end; causing him to have a heart attack and drop dead from the shock.
The Hikizuris discuss what to do with Kotani's body, and blame Narumi. It is revealed that she wasn't really dead at all and the "corpse" was just a mannequin that she set on fire instead. They decide to bury Kotani with the mannequin, and that from now on the Hikizuri siblings will live in peace together. Narumi says she can't believe they thought she was ever serious about killing herself.