A college student named Tohru Igarashi accepts a part-time job at a child care facility located deep in the mountains. The pay is an unusually high three million yen for six months of work, which immediately raises suspicions. Upon arriving, he meets a 14-year-old girl named Sakurako and a group of seemingly energetic children. The remote facility has no adult supervision, and Tohru soon discovers the grim truth: the children are not ordinary orphans but are tasked with the systematic murder and disposal of adults.

As night falls, the cheerful atmosphere transforms into extreme violence. The children become ruthless killers, forcing Tohru into a desperate struggle for survival. The narrative explores the psychological trauma that has turned these children into murderers and delves into their tragic backstories. The setting is an isolated village, cut off from the outside world, where sin runs deep and no one is allowed to leave alive.

The series spans two volumes, with the first focusing on Tohru’s introduction to the facility and the terrifying revelation of its true nature. The second volume attempts to resolve the plot, focusing on the efforts to escape or destroy the orphanage. A notable narrative point is the rushed conclusion, as the series was reportedly shortened by publishers, forcing the author to accelerate the ending. This leads to a finale that involves the deaths of key characters and a brutal resolution to the massacre, though some plot points feel underdeveloped.