In this presentation, I will share my work in progress project, “Ideology of Heritage, Museum, Cultural Politics, and Construction of National Identity in Finland and Japan”. This project focuses on the interviews of professionals in Finnish and Japanese national museums within the context of current social and cultural sustainability and decolonizing discourses. Through those current trends, the national museums in both nations face increased pressures on democratizing museum narratives and acknowledging the nations’ inconvenient histories, the ongoing coloniality of institutions, and the repatriation of cultural insignia. In the milieu of increasing conflicts between nation (state) and ‘diversifying’ society and culture, the interviews engaged questions like ‘Who is Finnish/Japanese?’, ‘What is Finnishness/Japaneseness to you?’, and ‘What is the role of (national) museums?’ The interviews shed light on how museum professionals see the changes in the societal roles of museums today. Some interviewees also challenged the idea of nation and culture to think beyond the dichotomies of national and cultural borders, pointing out the history of human (and cultural) mobilities throughout the history of humankind. We (including the cultures we live in) are all hybridized. Nonetheless, museums as powerful heritage-producing institutions have displayed race, ethnicity, and culture, ‘freezing’ them into a certain time and place in the frameworks of academic categorizations, e.g., anthropology, ethnology, art history and archaeology. This leads to my further questions, ‘What does it mean to decolonize a museum?’ and ‘What does sustainable development mean?’, which I will briefly touch on in this presentation. Although national museums in Finland and Japan face different struggles, the museum professionals in both nations shed light that they are, indeed, rebuilding the identity and practices of museums in order to open broader conversations within museums and beyond, diversifying narratives, and amplifying public engagements.