The importance of master protocol trials, which encompass basket, umbrella, and platform trials, has been increasingly recognized worldwide for their efficiency in evaluating multiple drugs or diseases within a single trial. While the US Food and Drug Administration and European regulatory bodies have issued guidelines to facilitate such trials, Japan only recently introduced its own set of guidelines to address the unique challenges and opportunities within its regulatory and healthcare landscape. Our study elaborates on these newly issued Japanese guidelines, which were developed through a collaborative effort involving biostatisticians, physicians, clinical trialists, regulatory authorities, and industry representatives. We provide a comprehensive overview of the guidelines, emphasizing their structure, content, and key considerations for effective planning and implementation. By highlighting the specific adaptations and innovations required to conduct master protocol trials in Japan, we aim to contribute to the broader discourse on optimizing clinical trial frameworks and enhancing drug development efficiency.