This Japanese country analysis is part of a series on the social entrepreneurship and social innovation ecosystems in Asian countries including China, Japan, South Korea, Singapore, Thailand and the Philippines. The comparative study provides a global analytical framework on characteristics, trends, challenges, and lessons learnt for building a supportive social enterprise ecosystem that leads social innovation in the different focus countries. According to the report, the development of the Japanese social enterprise ecosystem can be characterized by two milestones: the establishment of the Nonprofit Act in 1998 after the Great Hanshin-Awaji Earthquake and the Great East Japan Earthquake in 2011. After the Great East Japan Earthquake, unique ecosystem players that promoted social businesses emerged, which contributed to the diversification of support for social enterprises, particularly in accelerating the startup of new ventures. On a whole, in order to promote social entrepreneurship and to create innovative practices and policies, it is important to tackle issues related to corporate partnerships, the injection of private funds, and initiatives to foster social entrepreneurship at high schools and universities, and this Japanese case provides some learnings in this regard.