A backlash was growing in Hong Kong after Obscene Articles Tribunal ruled "Killing Commendatore", the 2017 novel by noted Japanese author Haruki Murakami, to be "indecent."

By Thursday, more than 2,100 people had signed an online petition backed by 21 activist groups for the censors to remove the categorization.

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Classifying the novel as indecent would "bring shame to Hong Kong people," the petition says, stressing that no other novels by the 69-year-old author have ever been classified as indecent in Hong Kong, Taiwan, or mainland China.

"If this is set to be a precedent case, Hong Kong would become the most conservative Chinese area," the South China Morning Post quoted the document as saying.

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'Explicit sexual details'

The latest Murakami book revolves around a portrait artist whose wife unexpectedly asks for a divorce. It features occasional sex scenes, similar to the author's previous works.

Earlier this month, the Office of Film, Newspaper and Article Administration in Hong Kong said they had received a public complaint about "explicit sexual details" in the novel, which they passed on to the censorship board.

A team from the Obscene Articles Tribunal subsequently labeled Killing Commendatore as indecent, and assigned it the second of their three-tier censorship rating. Exhibitors at the Hong Kong Book Fair, which ended on Tuesday, were forced to pull the Chinese edition of the book, and the novel was banned for readers under 18 in public libraries.

Similarly, bookstores are now obligated to present the book inside a wrapper that bears a legal warning, and only sell it to adults.

Murakami backed 2014 protest

Activists in Hong Kong fear that the censoring of Murakami's book is another attempt at stifling free expression in the former British colony.

There was no immediate comment from the Japanese author on the latest controversy. However, Murakami was one of numerous public figures who openly supported the 2014 Umbrella movement aimed at preserving Hong Kong's autonomy from the central government in Beijing.