This thesis investigates Japan's policy for energy transition towards renewables to mitigate its reliance on foreign fossil fuels. Analysis of CO2 intensity, sectoral energy intensity, total consumption, and renewables share vis-a-vis G20 peers’ reveals Japan's current status as a less green economy. Historical context underscores the pace of energy transitions, while examination of current and potential energy sources highlights promising avenues for future energy independence. Policy analysis, particularly the FIT policy post-Fukushima, demonstrates its role in promoting renewable adoption. Statistical models, including the Chow test and environmental Kuznets curve, confirm the policy's efficacy in boosting renewables' share. While there are ambiguity regarding the extent of the policy’s impact, the analysis provides supporting evidence for the promotion to renewable energy in the sectors analysed. The study suggests future research avenues using autoregressive models to uncover underlying determinants of structural energy transition shifts.