This article aims to illustrate the trajectory of Japan's security identity transposition. As one of the catalysts in identity transposition, it focuses on the constitutive roles of norms regulating Japan's overseas dispatches of the Self-Defense Forces (SDF). Whilst keeping the identities of 'a peace state' and 'a civilian power', the authors argue that Japan has crafted a new security identity after the end of the cold war and the 9/11 terrorist attacks*namely, 'an international humanitarian power'. As evidence of this transposition, the authors illustrate a dramatic increase in the number of overseas SDF dispatches on humanitarian missions, and the shift of domestic and foreign responses to it. The authors note that Japan has been on the road to remilitarisation and internationalisation during the past four decades through the enactments of laws for overseas SDF dispatches, the general public's shift of attitude on the SDF's roles, the evolution of the alliance in a more operational direction, and the creation of threats from North Korea