Your lengthy post while informative was predominantly Korean anti-Japanese rhetoric. There are people who have no idea that what you are saying is biased one sided charges.
I am Japanese born in Japan. Allow me to state some facts;
The Japanese of today are a mix of the original inhabitants
called Jomon who were making pottery in Japan as early as 10,500 BC. The Ainu of today are considered to be the decendants of the Jomon. The people who crossed over from the Korean penninsula the Yaoi started coming over in 300BC.
By looking at the number of years you can tell to what extent the original Jomon plays in the makeup of a modern Japanese. Without doubt the Yaoi invasion brought many new advanced technology, farming skills, etc. However, consider this; by 500-600 AD the Japanese(the Yamato) were a recognized seperate nation called Wa by the Korean states, and was an ally of Kudara (Paekche). Already the spoken language between Yamato and Kudara was completely different.
Today even Koreans say that Japanese look different from Koreans. If so the only explanation would be the extent of Jomon (Ainu) blood that exists in modern Japanese.
The Ainu of today are a mostly assimilated people with few if any "pure" ainu left. They were treated very much as the Native Americans were in North America. Now there is no bias
towards Ainu. Just as there is no bias towards Okinawans who
are far more Japanese than anyone realizes; their regional dialect is similar to very old Japanese prior to Chinese influence. The Okinawan word for Japanese is Yamatobito-
a Yamato person.