Promising improved student and teacher learning, Japanese lesson study has attracted many international educators to try to implement it in their own contexts. However, a simple transference model of implementation is likely to meet difficulties. Key determinants of any adaptation will be differences between existing conventions of pedagogy and of teacher professional development in Japan and the adapting country. These conventions will be reflective of underlying cultural differences. This paper reports a study the adaptations required to increase the transferability of Japanese lesson study for use in the Philippines. Hofstede's dimensions of national culture are utilised to identify and analyse the incongruences in cultural orientations between Japanese and Philippine teachers, which may explain the adaptations needed in order to implement lesson study in Philippine schools. Sensitivity to cultural challenges during the process of adaptation should increase the chances of successful implementation to the benefit of Philippine teachers.