Japan has historically been fairly xenophobic. It's pretty nice to tourists though (can personally attest to that).
However, I have several friends in Japan for work who have stated the discrimination they face for not being Japanese. The fact that they're nearly fluent in Japanese doesn't seem to matter as much as they're white, black, or a different asian. They have trouble finding places to live if they need to move as suddenly available apartments get filled up when they apply, their neighbors don't talk to them, and some other things that annoy them.
japan is pretty xenophobic
however... who fucking cares?
Japan is notorious for being xenophobic, it doesn't matter whether you're white, black, brown or whatever - if you aren't Japanese then they'll have an issue with you.
Not all Japanese people are that way though - it's mostly the older generations since a lot of the younger adults and teens in Japan actually have a lot of interest in other countries and foreigners in general. The only way I know this is I have a Japanese friend who told me about a lot of this stuff and a lot of younger Japanese people want to meet us and talk to us but the language barrier is often why we don't see many of them on English speaking websites. So that's a bit of fun trivia for you!
I think the real question is who cares? They aren't Muslims and it's not s Muslim country, so as long as you're not gonna get tortured and beheaded within hours of arriving, just enjoy yourself
I would stop worrying about what people say on Youtube, and follow your dream. I'm sure there would be many girls there who love white guys. You'll never know until you go. Life is about taking chances.
They've disliked Americans for a long time, it's nothing new. Brits they're kinda okay with. Like Fox Queen said WWII is part of that, but younger generations who weren't alive at the time aren't nearly as "anti-white". Though ww2 aside many people there do still consider Americans to generally be boorish fat obnoxious idiots, just as people do in many other parts of the world too, and rightfully so.
I don't think they dislike foreigners, in fact, mind you i haven't met many Japanese people, but some of them are quite fascinated with American people and the culture.
What i could imagine is drunk douchebags getting into fights outside of night clubs, disrespecting the culture etc. Now that is a problem that could give us foreigners a bad rap, especially for Americans.