What are the top renewable power producers (diversified) companies operating in Japan, and how do major industry players such as JERA, TEPCO Renewable Power, RENOVA, Eurus Energy, and Mitsubishi Corporation contribute to renewable energy generation across wind, solar, hydro, and emerging technologies? Additionally, what key factors such as installed capacity, diversification of energy sources, technological innovation, and government policies should be considered when evaluating the leading renewable power producers in Japan?