Wikipedia page about this book: https://en.wikipedia.org/wiki/Diary_of_a_Madman_(Lu_Xun)

Release date is 2008-05-02

"狂人日記" by Xun Lu is a short story published in 1918. Written in vernacular Chinese, this groundbreaking work follows a man's diary entries as he becomes convinced that everyone around him—family, villagers, and society itself—practices cannibalism. Through his increasingly paranoid observations, he discovers references to "eating people" even in ancient Confucian texts. The story uses madness as a lens to critique traditional Chinese culture and values, concluding with a desperate plea to "save the children" from a society trapped by oppressive customs. (This is an automatically generated summary.)

Original publication data not identified