Sonbi refers to a social class of people, particularly of the Chôson dynasty, who, if they passed the civil service examinations and became bureaucrats, served the king and worked in politics for the people, and once they retired would teach at an academy and train the next generations, making efforts to realize Confucian principles in society. While Sonbi served the king with loyalty, they also upheld a universal “principle,” such that if the king committed wrong, they remonstrated, and if their remonstration was not heard, they resigned from their post without hesitation. The relationship between king and Sonbi was bound by “duty” (giri), and Sonbi were not completely subordinate to the king. In this respect, their relationship differs from the lord-vassal relationship developed in samurai society of Japan. For example, if a vassal remonstrated to his lord over wrongdoing and was not heard, the famous Yamamoto Tsunetomo, author of Hagakure, would probably urge him to serve his lord, including all his faults, all the more. In the Edo period, there were bushi (warriors) like those depicted in Hagakure, who lived paying homage to their lord and shared in their lord’s fate. On the other hand, during this “peaceful age,” there were others who attempted to define the reason for the samurai’s existence through Confucian thought. Whether they lived as samurai, as gentlemen, or as a combination of both, the identity of Edo period bushi was in flux. In this paper, I took up three bushi (Yamaga Sokô, Ogyû Sorai, and Nyûi Mitsugi) of Tokugawa Japan, who lived a dual identity of both Confucianist and bushi. The societies of Tokugawa Japan and Yi Dynasty Choson differ in political system and structure, and so sonbi and bushi cannot be compared hastily. However, there is a common element in both groups as ruling classes who strived to live up to the spirit of noblesse oblige and to lead society. In that sense, examining one portion of noblesse oblige among Japanese bushi, can offer hints that shed light on the spirit of sonbi. Nyûi Mitsugi, a magistrate of the exchequer in Hirosaki domain, carried out administrative and financial reform within the domain as a practician. At the same time, Nyûi was also a Confucian who learned from Yamaga Sokô and Ogyû Sorai. I considered how Sokô and Sorai recast the concept of the bushi in a peaceful society of the Tokugawa period, and examined the case of Nyûi, who was deeply committed to their thought and carried out actual reform in domainal politics. I also paid attention to the awakening of Nyûi’s “private” consciousness as ethical subject, of a bushi that upheld the “public.”