Mac-2 binding protein glycosylation isomer (M2BPGi) is a liver fibrosis biomarker that originated in Japan and has been covered by health insurance for 10 years. M2BPGi is useful not only for liver fibrosis stage prediction but also for assessment of the degree of liver inflammation and prediction of hepatocellular carcinoma development. The usefulness of M2BPGi for assessing disease progression in patients with various chronic liver diseases has been demonstrated over the past decade in a large number of patients. Recently, there have been many reports from outside Japan, including reports from South Korea, Taiwan, Hong Kong, and China. These studies demonstrated that M2BPGi is an excellent biomarker that can evaluate the progression of liver fibrosis in chronic liver disease. It is also an excellent indicator of liver activity. Recently, a quantitative M2BPGi (M2BPGi-Qt) assay was developed, and future validation in real-world settings is expected. This will enable diagnosis of the progression of liver fibrosis based on more precise test results and is expected to contribute to the early detection and follow-up of diseases caused by chronic hepatitis, as well as post-treatment monitoring. The significance of the M2BPGi-Qt assay will likely become clearer as real-world data accumulate. If new cutoff values for each chronic liver disease stage and activity level using the M2BPGi-Qt assay are set based on real-world data, it is expected that this will become a useful tool to identify cases of liver fibrosis and monitor the progression of chronic liver disease.