TOKYO (Reuters) - Kansai Electric Power Co said its 1,180-megawatt No. 4 reactor at its Ohi nuclear plant resumed supplying electricity to the grid on Saturday, Japan's second nuclear unit to regain power since last year's Fukushima crisis led to the shutdown of all units.

The move came three days after the unit was restarted, and the reactor is set to begin full-capacity power generation around July 25-28.

Japan ended two months without nuclear power on July 5, when the Ohi No. 3 unit resumed power output for the first time since a nationwide safety shutdown that followed a massive earthquake and tsunami in March 2011 that crippled the Tokyo Electric Power Co.'s Fukushima nuclear complex.

Japan had idled the last of its working reactors in early May, leaving the country without nuclear power for the first time since 1970.

All but two of the country's 50 nuclear reactors have been offline for checks amid concerns about safety, and the gap is being met by firing up costly fossil fuel units and through energy-saving steps.

(Reporting by Osamu Tsukimori; Editing by Ed Lane)