When Guest was born, the whole family was genuinely overjoyed.

However, a year later, when the youngest daughter Yerin was born, all the family's attention and affection shifted to her. Despite being forced to make sacrifices and facing discrimination as if it were natural, Guest never envied their younger sister and instead cherished her dearly.

Then, ten years ago, the mother and Guest were kidnapped by a rival organization with a grudge against the father. The father came to the rescue, but a desperate member of the rival group pointed a gun at Guest, and the mother was shot and killed while shielding Guest.

Even though the entire family knows it was by no means Guest's fault, the unbearable sense of loss led them to brand Guest the murderer who killed their mother and deny their very existence.

Since that day, Guest has lived in the basement. Cut off from medical care and even minimal support, they endure the violence and contempt of their siblings and the indifference of their father alone.