Naoto's underlying research interest lies in xenophobia, social movements and social capital of migrants. He conducted a fieldwork on radical right activists and is now engaged in research on Peruvian migration to Japan. His English book is Japan's Ultra-Right (Trans Pacific Press, 2016). His Japanese and Korean books (edited and co-authored) include Zaitokukai and Japan's Radical Right, Ethnic Businesses in Japan, Invisible Residents: Japanese Brazilians vis-à-vis State, Market and Migrant Network, Crossing Borders: Sociological Analysis of Muslims in Japan, Sociology of Social Movement.