The recent development of Japan's high-speed rail projects in Southeast Asia may suggest the shinkansen is leaving the center of its railway diplomacy.
Beijing began to export its own HSR systems overseas under the Belt and Road initiative in the last decade. Meanwhile, the Abe administration since 2012 has promoted the shinkansen overseas as a countermeasure to balance China's geopolitical influence. Prior to the 2010s, Japan only exported the shinkansen once, to Taiwan in 2007. For its proponents, the shinkansen's safety record, high efficiency, and other excellent performance measures justify its higher cost compared with the Chinese HSR.
With regard to Sino-Japan HSR competition, Southeast Asia is the main battlefield.