Japanese energy and climate policy stands at a critical junction at present and we may need innovative policies from different approaches. The idea of personal carbon allowances (PCA) system which has been under discussion in Europe is one of the innovative policies to surmount the issues. The authors have proposed Fit-PCA suitable for Japan in which the carbon allowances are distributed to all the people equally and they can be traded in a fixed price. In this study, a case study has being conducted for half a year in cooperation with 30 households to investigate how they change their energy saving behaviors, pro-environmental attitudes and behaviors. The case study is still ongoing, and this paper reports the progress.