"The No. 1 and No. 2 reactors at Fukui Prefecture's Oi nuclear power plant are the most dangerous in Japan, according to a cross-party group of lawmakers opposed to nuclear power."
You can read about the Oi Nuclear Plant here http://en.wikipedia.org/wiki/%C5%8Ci_Nuclear_Power_Plant
Japan plans on re-starting reactors 3 and 4 at Oi. Next likely re-start on the agenda is Ikata.
"Two seismic experts publicly warned that the government is under-estimating the threat to these reactors which are located very near a seismic fault. And a group of lawmakers cutting across political parties released a danger ranking of 50 nuclear reactors in Japan calling for their phased decommissioning." (Varma http://timesofindia.indiatimes.com/world/rest-of-world/Experts-warn-against-restarting-nuclear-reactors-in-Japan/articleshow/14473347.cms )
"The nuclear power plant in Ikata, operated by Shikoku Electric Power Co., is currently seen as a likely candidate to be the next nuclear reactor to be restarted." (Westlake http://japandailypress.com/tag/fukui)