People generally work in the fuzzy areas in which values fostered by different entities do not always match, which sometimes cause dilemmas and create alternative values. This study examines professional ethics and identity at work, by specifically exploring the experiences of Japanese international development practitioners who work in such a grey area. These practitioners work in projects that theoretically aim to support the development of less-developed countries, while on a practical level they must also serve the Japanese side. The individual ethics, which are developed when challenged by alternative ethics from the outside world, are deeply embedded in their professional identities. By Looking at the ways in which their work ethics are fostered and related to their professional identities, the study reveals that each professional fosters his/her own ethical identity. This study expands our understanding of the formation and emergence of professional identity.