This chapter casts an exploratory eye on this rather neglected aspect of Japan's strategic thinking in the twenty-first century, as the rising and declining of great powers dramatically reshapes the strategic landscape in which Japan rose as the first so-called Asian giant in the wake of World War II. It explains the emerging concept of the Indo-Pacific and Japan's preference for the term koiki Ajia (broader Asia), which recognises geographic extension rather than replacement of strategic thinking. Japan is a key element in the Indo-Pacific concept as articulated in American, Australian and Indian writings. Most significantly, in 2013 the Japan Institute of International Affairs (JIIA) completed a project examining the meaning and significance of Indo-Pacific in the context of the South China Sea and the Indian Ocean. Together with a third power shift the slower rise of India as another Asian giant their geostrategic ramifications have oriented Japan towards the Indo-Pacific concept.