Kansai Electric Power's plan next month to relaunch the last idle reactor at its flagship nuclear plant, capping a year-long series of restarts, will mark an energy shift in Japan with the sharpest drop in liquefied natural gas (LNG) imports since the Fukushima disaster.

Japan, the world's top buyer of LNG, was forced to sharply increase its purchases of the superchilled fuel after the 2011 disaster, which led to the shutdown of all 54 of its nuclear reactors.

While LNG imports have ebbed from their peak in 2014, as a smattering of reactors came back online and Japan boosted its use of renewable energy, Kansai's latest plans — including a reboot of the No.2 unit at its Takahama nuclear facility on Sept. 15 — will help to accelerate the fall this year to nearly 10%, analysts say. The repercussions, moreover, will extend beyond Japan.