In February 2023, the first national conference on Diagnostic Excellence was held in Japan. As the conference covered a wide range of academic areas, we placed particular emphasis on topics related to excellence in physicians’ clinical reasoning. This focus reflected the culture of Japanese medical professionals, especially of physicians, who have shown passion for clinical diagnosis for decades, having held non-profit voluntary multi-institutional conferences during off-duty hours. Of the over 1,400 participants who attended the two-day conference, 80% were generalist physicians and residents, 10% were medical students, and the remainder were healthcare professionals and participants from other academic areas. Given the background of Japanese physicians’ passion for clinical diagnosis, the conference organizers believed that focusing on the diagnostic thinking of physicians as part of the Diagnostic Excellence concept would have strong appeal to participants. Simultaneously, the organizers believed that it was important to target participants in their 20s–40s, and made efforts to utilize social networking services and advertising strategies, including creating individual posters with the help of professional designers. On reflection after the conference, consideration of the local characteristics of the population, particularly their interest in the target population, and the expansion of the conference’s focus to include younger participants may have served as drivers of the success of the conference. This outcome of the conference in Asia is an intriguing step in the world deployment strategy of Diagnostic Excellence, and is expected to promote cooperation among Asia and the United States, Europe, and Oceania.