Doraemon has gained widespread popularity. The character was introduced to Vietnam in 1992 through Thai-translated comic books and later on the television series in 2000, becoming particularly popular among generations of Vietnamese children. This article examines Japan’s soft power with the case of the Doraemon brand in Vietnam. It focuses on three aspects: (i) Japan’s use of popular culture to promote its soft power; (ii) the development and localization of the Doraemon brand in Vietnamese cultural life, with particular attention to people-to-people exchanges and sustainable development; and (iii) the stakeholders involved in the Doraemon case as part of Japan’s soft power strategy. Drawing on documentary research and the case of Doraemon, the findings indicate that Doraemon functions as a cultural resource of Japan’s soft power in Vietnam. The character’s widespread dissemination and reception have not only contributed to the promotion of Japanese culture but have also strengthened people-to-people exchanges, supported cultural diplomacy, and reinforced a positive image of Japan among the Vietnamese public. Japan’s experience with Doraemon suggests that Vietnam could develop its own popular culture ecosystem by creating distinctive cultural images and symbols, thereby enhancing its soft power.