This paper outlines the recent expansion of the utilization of medical real-world data (RWD) in the clinical development and post-marketing evaluation of drugs in the United States, European Union, and Japan. We provide an overview of the necessary knowledge for researchers to understand the capabilities and limitations of RWD compared to clinical trials. Recognizing the importance of daily clinical practice is essential for effectively utilizing RWD, and it is crucial to formulate relevant research questions that can be addressed using this data. The paper covers key areas including: ① data sources of RWD, ② pharmacoepidemiology, and ③ pertinent laws for using RWD in Japan. Under the common understanding of the difference between non-interventional studies with RWD and clinical trials, the paper discusses the challenges and future prospects of using medical RWD in Japan and suggests statisticians to prepare enhancing knowledge of daily medical records and handling of log formatted unstructured data for these challenges.