He is especially interested in early childhood teachers' professionalism, qualitative research methodology in early childhood education and care, collaboration between early childhood teachers and researchers, emotional practice of early childhood teaching, design of case conferences for early childhood teachers, methodologies for understanding a young child, and the relations between the quality of early childhood education and care and young children’s development. Professor Nakatsubo’s research has been published in Current Issues and Best Practices in Early Childhood Education, Asia- Pacific Journal of Research in Early Childhood Education and International Journal of Early Childhood Education.