The Japanese and Vietnamese have borrowed a great deal from Chinese culture over a long period of time. One result is that Chinese words and Chinese names borrowed by these languages are conventionally read with native versions of the original Chinese pronunciation. The differences between readings in the three languages can be quite large due to (1) regional differences in the source of borrowing, (2) adaptation to the native phonology, and (3) changes in all three languages over the years.
The following table shows the modern Mandarin, Japanese, and Vietnamese pronunciations of some of the Chinese names and concepts that appear in 'Days of the Week in Chinese, Japanese, and Vietnamese'.