This paper addresses the urgent and understudied issue of how to protect migrants stranded by disasters in their countries of destination, focusing on the roles of institutions and state actors in migrant-receiving nations. It explains how migrant displacement can be understood in terms of international norms concerning internal displacement. Then, it argues that the migrant-receiver state bears the primary responsibility for protecting displaced migrants who fit the category of “internally displaced persons (IDPs)” and assisting their short- and longer-term recoveries. A case study of Japan illustrates how these concepts are adopted in a real situation. Overall, this disaster-prone nation has been fulfilling its protection duties toward the vulnerable migrant population by building inclusive and equitable protection mechanisms. But, such activism is more salient at lower levels than at the upper level of the state. Highlighting the legal, normative, and institutional gaps of migrant protection from disasters at international and national levels, this paper elucidates the merits of considering at-risk migrants as IDPs and their host state as the primary guardian, so as to build a more adaptive and resilient disaster mitigation framework in culturally diverse environments.