A Japanese hotel chain is allegedly to have provided books which openly deny the Nanjing Massacre in China and forced prostitution in Korea during World War II, sparking outrage on Chinese social media.

The books are written under the pen name Seiji Fuji by Toshio Motoya, CEO of the APA Group which runs the hotels.

A hotel staffer told the Global Times that the books could be found in drawers in every APA hotel room in Japan and are available for sale.

Motoya, 73, is also the deputy director of a support group for Japan's Prime Minister Shinzo Abe, and the "right wing" background of the hotel previously has been exposed on Japanese social media.

As of September 2016, there were 413 hotels or resorts and almost 70,000 hotel rooms under the APA Group.

A Sina Weibo account named "KatAndSid" first exposed APA selling such books on Thursday. They then posted a video of them purchasing one of the books, Theoretical Modern History II - The Real History of Japan, at the reception of an APA-owned hotel.

The book refers to the "300,000 people slaughtered in Nanking (now known as Nanjing)" as "falsehood" and labels the Nanjing Massacre, "comfort women" and forced prostitution in China and South Korea as "untruths."

More than 450,000 users had forwarded the video as of press time, including the official Sina Weibo account of the Central Committee of the Communist Youth League.

An employee with Chinese travel giant Ctrip said Monday that the company had noticed the news and was planning a response, but some have already responded.

Jia Zhengfei, head of a Japan-based company, said that his company will stop providing services for reservations to APA hotels, unless the hotel withdraws the books and Motoya apologizes publicly.

Japanese troops captured Nanjing, then China's capital, on December 13, 1937 and started weeks of slaughter.

At least 300,000 unarmed civilians and Chinese soldiers were murdered in the ensuing atrocity, and over 20,000 women were raped. According to a Japan Today report on January 10, a record 24.04 million tourists visited Japan in 2016, with the biggest numbers coming from South Korea and China.