The emergence of technology-oriented agreements such as the 2005 AsiaPacific Partnership on Clean Development and Climate (APP) may have significant implications for the future of global climate governance, as these agreements could be perceived as an alternative for the existing international climate regime. It is, therefore, important to examine what has moved countries to be involved in these agreements alongside the UN climate regime. This article seeks to identify possible factors contributing to Japan's participation in both the UN climate regime and the APP, looking at the position of domestic interest groups, the distribution of climate policy-making at the government level and varying international pressures. It concludes that Japan's participation in both the APP and the UN climate regime flows from a policy-making process that tries to accommodate conflicting viewpoints at the domestic and international levels. To what extent Japan's participation in both fora can be regarded as constructive will depend on the partnership's ability to support the implementation of a future climate regime.