>>28110588Red and Blue Oni are actually just European sailors who got washed up in Japan, white skin is somewhat blue (particularly with regard to the visibility of veins think blue cheese) compared to native Japanese skin and Red comes from sunburn. The tendancy for them to be depicted as marauders comes from the sailors turning to banditry because of inability to assimilate largely due to linguistic barriers as well as superstitious xenophobia.
Or not, I just made that up 
