Softbank proposal for solar power generation. 36 of 47 prefectures have signed up, also Osaka, which relies heavily on nuclear power.
Son, the president, said "setting up solar panels on 20 percent of unused or abandoned farm land can have the generating capacity of about 50 gigawatts, equivalent to the output of about 50 nuclear generators."
"By aiming also to introduce other energy sources, such as wind and geothermal power by 2020, Son envisions raising the share of renewable energy in Japan to about 20 percent of total electricity generation." Japan Times, July 13, 2011.

Note that no-one has proposed replacing all nuclear generators. The energy demands of Japanese industry are so large that this would be impossible with the present state of engineering knowhow.