Your friendly, neighbourhood bobbies on the beat
Apparently this is a flyer published by the friendly boys in blue from Ibaraki. Just a quiet note to the locals that states the best policy when dealing with the influx of foreigners, all of whom are criminals, is to "stop them at the shores!"
Yes, that is a total of 7 riot police subduing one helpless chap (well, 6 and their mate on his way in to help out)...
Just in case you're wondering, the first 3 kanji in yellow say "gaikokujin", or foreigner. And I thought Japan was a friendly place.
For more see the newspaper report here.