For a movie about a particularly dark chapter of China’s history, 731 has been doing exceptional business.

The film, released on Thursday, focuses on Japan’s Unit 731, which conducted biological warfare in northeastern China during the second world war, using disease prevention research as cover to kill civilians.

It has topped the Chinese box office, taking more than 1.1 billion yuan (US$154.6 million) in revenue by Sunday, according to Lighthouse Professional Edition, a Chinese box office website.

The film’s release is the latest in a series of events to mark the 80th anniversary of Japan’s defeat in the war and comes as each country’s perceptions of the other has declined – a situation some say will be exacerbated by the movie.

The film follows the story of a group of people imprisoned who try to escape from the facility.

731’s premiere coincided with the anniversary of the Mukden Incident on September 18, 1931 – the beginning of Japan’s invasion of China.