I was there in oct last year... had a absolute ball...
Tokyo - It's pretty overwhelming at first, just try and fully immerse yourself in the culture of it.. I regret not doing that, the girl I went with was too scared do so and buggered up that part of the trip.
If you get the chance go to Kyoto there are soooo many beautiful temples there and maybe try and take a day trip to Nara, where the biggest wooden temple in the world is and HEAP of cute little deers who will turn nasty and ear your clothes once you run out of biscuits to give them.
Golden Pavillion is a must see. And you might spot a few geishas down the back streets of Kyoto if your lucky. There were plenty of other "ladies of the night" there done up to the max to entertain the business men.
I hardly saw any modified cars around, I got excited every time I did see a skyline.
If you go to Harajuku make sure you go on the weekends. Thats when all the Harajuku girls are out.
I didn't find the Japanese racist at all. Some got a little irritated trying to explain things to me because I couldn't understand but in general I found them most accommodating and patient. it pays to know a few Japanese words, especially "thank you" and "excuse me". I think I used those the most.
Otherwise just go with no expectations and it will totally blow your mind! and the girls over there are STUNNING and so fashionable.
Have a awesome time!