Operating Status of Japan's Nuclear Plants

http://www.fepc.or.jp/library/data/operation/plant/index.html

You'll see a map with clickable Japanese plant names.  You'll just have to compare to some other source to identify the one you want.  After you click that, you will need to click the first blue link, it has the Japanese words 発電機出力, which means electric generating unit power output.  There is more data than that, so ask me if you want more clarification, although translating tools might get you there anyway.  Once you click on that, you will get a new window with a table showing the reactors at the site you clicked on, and you will see units of 万kW.  Japanese groups numbers in 10,000s instead of 1000s like we're used to, so if you see 82万kW for instance, that means 820,000 kW.  First column with these units is the current output and 2nd is capacity.

The companies themselves also have real time monitoring sites for their plants.  I don't know if this is true for all plants, but it is for most at least.  I tried to answer your question going through those first.  It's a mess:

http://www.tepco.co.jp/fukushima2-np/monitoring/unten.html
http://www.tepco.co.jp/fukushima1-np/monitoring/unten.html (umm... think sytem's broken)
Onagawa:
http://www.tohoku-epco.co.jp/electr/genshi/onagawa/hd.html
Higashidori, Tohoku power:
http://www.tohoku-epco.co.jp/electr/genshi/higashi/hd.html
Higashidori, Tepco: don't have
Kashiwazaki Kariwa:
http://www.tepco.co.jp/kk-np/monitoring/den-j.html
Tomari:
http://www10.hepco.co.jp/gen_out_realtime.html
Shika:
http://atom.pref.ishikawa.lg.jp/monitoring/Pages/Npp/FormNppGraphOutput.aspx
Tokai, don't know.
Tsuruga:
http://www.japc.co.jp/pis/tsuruga/unten.htm
Mihama:
http://www.kepco.co.jp/localinfo/live/n_unten/unten_40.htm