Japan’s overall AI capability ranks in the world’s second tier. Nevertheless, through a structured science and technology diplomacy approach, it has effectively enhanced its international influence in this field by employing three strategies: institutional participation, discourse construction, and practice sharing. At the institutional level, Japan has actively promoted the “alignment” of AI governance principles among the OECD, the G7, and the G20 and has introduced the “Data Free Flow with Trust” (DFFT) framework as a supporting mechanism for AI governance. At the discourse level, Japan prepares draft texts for international AI discussions to highlight its national interests in international rule-making. At the practical level, Japan shares with the international community its governance practices characterized by a “soft law paradigm” and “agile governance,” thereby attracting international recognition. Through the interaction among these three approaches, Japan has shaped its international image as an “active actor” in global AI governance, helping to strengthen its international discursive power.