This article examines the extent to which or how self-identified great powers resort to military aggression following events that challenge their sense of greatness. It problematises the prevalent notion that great powers and events exist and have effects independently of the narratives that constitute them. The article does this by engaging with Ontological Security Studies, Great Power Narcissism, and the psychology of vulnerable and grandiose narcissism, as well as by analysing Japanese identity narratives in two periods seemingly marked by equally challenging events – the Meiji era (1868–1912) and the post-war period (1950–71). It finds that Japan’s military aggression against China in 1894–5 was enabled by vulnerable narratives of shame and insult, while the decision to wage war with Russia a decade later was facilitated more by grandiose narratives. Despite Japan’s overwhelming defeat in the Second World War and the persistent desire among conservative elites for great power status and identity, however, overall post-war narratives did not feature similarly negative emotions and calls for revenge. Japanese great power aspirations were arguably curtailed in this period through intense narrative contestation, notably progressive counter-narratives featuring more self-reflective expressions of guilt and remorse, and even the self-reflexive desire for a non-great power identity.