Other then the fact that Japan annexed Korea and absorbed their culture and government into the Japanese empire during the 1900s and treated them with extreme cruelty, violence, and racism that is akin to the holocaust, nothing much.
Korea and Japan have a history of atrocities dating back to late middle ages iirc.
There's some quite interesting stuff. For example the legend of Yi Sun-Sin and the less nice stuff.
Chinese butchered each other, buddhists and vietnamese, southeast asian nations butchered each other because there were atleast 4 different religions all mixed up what is now thailand-malaysia area.
The japanese committed some of the most well known atrocities like the rape of nanking against the chinese.
In short, not really any different from any other place in the world. Just very well documented for a long time.
I actually get upset when I see the Japanese flag when I browse 4chan and there isn't something incomprehensible written in broken English underneath it.
**gentlemenmew used "*roll picture*"** **gentlemenmew rolled image****gentlemenmew used "*roll 1, 1-99*"** **gentlemenmew rolls 42** and its still funny in reverse
like yours for example
Eh, most of Japan's on 2ch or 2chan (I can never remember which is the popular one) rather than 4chan. I'd imagine there are more similar sites for different countries.