The Madman is a minor government administrator living in a small Chinese village. He documents his escalating fears of cannibalism and societal collapse in a vernacular diary. Convinced that his neighbors and family are plotting to eat him, he frantically consults history books and observes those around him for signs of conspiracy. His observations blur the line between clinical paranoia and acute social critique as he questions the foundations of his culture.

Elder Brother is a traditional figure who upholds the strict Confucian hierarchy within the family and village. He adheres rigidly to historical precedents and social norms, firmly believing that children owe their parents ultimate devotion. He views his younger sibling's fears as delusional and maintains the status quo with a serene, unquestioning demeanor.

Old Fifth Chen serves as an attendant to the family. He occupies a low rung on the social ladder but actively protects the existing power structure. Whenever discussions of cannibalism or social reform arise, he becomes distressed and physically removes The Madman from the situation. He prefers to hide problems behind locked doors rather than confront them.

Mr. Gu is a rural villager who never appears directly in the present events of the diary. He exists in the narrative as a figure from the past whose account books were trampled on by The Madman. He stands in for the countless ordinary citizens exploited by minor government bureaucrats over the centuries.

An educated man visits his hometown after hearing rumors of his old friend's severe illness. He serves as the framing device for the story, writing the introduction in classical Chinese. He accepts the diary from Elder Brother and presents it to the reader without providing his own alternative version of the events.

The deceased sibling of the two brothers exists only in the memories of The Madman. He obsesses over the circumstances of her death. Her fate becomes deeply entangled with his fears regarding the family's adherence to traditional, hierarchical obligations.

A local youth crosses paths with The Madman on the street. When interrogated about the morality of cannibalism, he is evasive and dismissive. He brushes off the questioning by insisting such things only happen in famine years, reflecting the younger generation's inherited complacency.

A medical professional arrives at the family home to treat The Madman. He conducts his examination while quietly consulting with Elder Brother. The Madman overhears his medical advice to eat something quickly and wildly misinterprets it as proof of a cannibalistic conspiracy.

A domesticated animal living in the village glares at The Madman on the street. The Madman fixates on the dog, fearing it intends to attack him. The animal represents the terrifying possibility of de-evolution, standing as a constant reminder that trained creatures easily revert to their primal instincts.