With an increasingly large number of Chinese tourists in Japan, the hotel industry is in need of an affordable market research tool that does not rely on expensive and time-consuming surveys or interviews. Because this problem is real and relevant to the hotel industry in Japan, and otherwise completely unexplored in other studies, we have extracted a list of potential keywords from Chinese reviews of Japanese hotels in the hotel portal site Ctrip1 using a mathematical model to then use them in a sentiment analysis with a machine learning classifier. While most studies that use information collected from the internet use pre-existing data analysis tools, in our study, we designed the mathematical model to have the highest possible performing results in classification, while also exploring on the potential business implications these may have.