ABSTRACT With Japan’s new connectivity initiative, the Free and Open Indo-Pacific, alongside several previous doctrines, Tokyo has started to shift its regional security policy focus towards democratic states in the Asia-Pacific. Qualitative case studies on bilateral and multilateral cooperation in the Indo-Pacific assess these changes as reflecting a more proactive security policy initiated under the Abe administration (2012–2020). While Tokyo’s security policy towards Southeast Asia has certainly changed both qualitatively and quantitatively since 2012/2013, explaining this change by referring solely to Prime Minister Abe’s foreign policy agenda falls short. Rather, Japan’s new strategy is the result of a change in perceptions among executive officials in the foreign and defense ministries that had already been initiated in the 2000s. This study looks at this development and examines the role of the Prime Minister’s Office of Japan (Kantei), the Ministry of Foreign Affairs (MOFA), and the Ministry of Defense (MOD) in initiating the change and assesses Japan’s Pacific strategy through an interview-based qualitative case study. Using the concept of “foreign policy analysis” and based on official publications and interviews with representatives of the MOD, the MOFA, and Kantei advisors, this study expands the qualitative aspect of existing research and shows that the origins of this new regionalism are found primarily in the changing perceptions of executive officials. It also points to the importance of analyzing administrative executives at the interface among Kantei, the MOFA, and the MOD, which can shed new light on the reasons behind Japan’s regional strategy shift.