Well I assume the Japanese are still slightly ethnocentric. Since they were so heavily in the past. Take gaijin (ナ?Oツ人) for example. It's used for anyone not of the Japanese race. Some find it offensive to be pointed out strictly as a foreigner, but I do not believe the Japanese mean it (today) to be offensive. The word itself (historically) is all over the place, and in the past might have been used as an offensive term, but I'm getting besides the point.
The Japanese really had the upper hand over East Asia. Just as you said, Devious, "The refusal of many in the Japanese right-wing to admit to their country's past wrong-doing is a continuing source of tension between Japan and its neighbors, especially China and South Korea." Because of the conditions Japan was left in after World War II, they were forced to depend on foreign workers and international cooperation. They felt that, particularly the Zainichi (Koreans), were disloyal and the cause of riots. "Earlier, in 1986, Prime minister Yasuhiro Nakasone had gained notoriety for proclaiming that Japan was successful because it did not have ethnic minorities, like the United States. He then clarified his comments, stating that he meant to congratulate the US on its economic success despite the presence of 'problematic' minorities."
I don't know if the Japanese goverment and politicians still think like that, times do change, but I do not believe the average Japanese still perceives other Asians as such. I don't have any real proof, but considering how often artists will go to Korean, or Shanghai, or Taiwan... they can't think to poorly of them.
So to answer a previous question, Miyavi being mixed might cause some type of trouble. From the stand point of their past beliefs, it's almost like Harry Potter. Purebloods and all that. Japan is the Slytherins frowning on any of mixed or tainted blood.
Still, I do not believe many care that much about it anymore in present day Japan.
Any pictures of Miyavi with blonde hair would be a recent picture. Multicolored, silver (well that could be hard seeing as his NEWEST hair is silver, but there's been no real photos as of yet), or black, or blue, or green, or whatever colors he's had his hair, are all old. Be careful though, there's one very old photoshoot of Miyavi w/ "blonde" hair.