The protagonist and her family moved to a picturesque resort city to live. Upon the invitation of their friendly female neighbor, they joined a “big family” composed entirely of people from outside the city. Although the members of this big family were not related by blood, their bond was stronger than that of family, and their relationships were harmonious, giving the protagonist’s family a sense of warmth and belonging. However, the good times didn’t last. After some time, the protagonist learned that the gathering place where they often held their parties was actually a mu*der house. Two years ago, a bizarre homicide had occurred in that house. The female neighbor had been organizing gatherings at her place out of fear. This revelation cast a psychological shadow over the protagonist, but she didn’t anticipate that even more terrifying things would follow. After they moved there, one member after another of the big family started getting killed. The police investigation confirmed that the culprit was someone familiar to them. The protagonist couldn’t understand why such things were happening. Who was the killer, and what was their motive for the mu*ders? As the investigation progressed, an unexpected truth gradually emerged.