Abstract: In recent years, Japan’s foreign policy elite has started to increasingly securitize China in their security discourse. The harsher tone from Tokyo is widely evaluated as a direct reaction to China’s own assertive behavior since 2009/2010. Yet, the change in the Japanese government’s rhetoric had started changing before 2010. In order to close this gap, the present article sheds light on an alternative causal variable that has been overlooked in the literature: a change in Japan’s security institutions, more specifically, the upgrade of the Defense Agency to the Ministry of Defense, in 2007. While utilizing discursive institutionalism and securitization-approaches, the present article demonstrates that a strong correlation indeed exists between the institutional shift and the change in Japan’s defense whitepapers in the 2007–10 period. It thus opens up a research avenue for the further scrutiny of the hitherto understudied but significant causal linkage in the study of contemporary Japanese security policy toward China.