Zhi chi

The movie is an adaption of The Wisdom Tooth, a 2015 book by Chinese novelist Lei Mi. Director Soi Cheang tried to make a movie out of it in continental China but couldn't, so he set this project aside. A few years after that, he came back to Hong Kong and set out to make a smaller-scale movie (as he was used to direct the Monkey King movies in China). He thus gave the novel to his writer Kin-Yee Au, so that he would adapt it into a movie, while relocating the action to Hong Kong.