Without doubt, it's the Japanese.
I've traveled all over the world but the year I spent in Japan is the only place I've lived that was overtly racist against basically all other races.
I remember once waiting for a lift with the lovely Junko when some mid-50s guy in suit came to wait for the lift. He looked at Junko, said something and she just bowed her head and stared at the floor. I asked her what he'd said but she just shook her head. He didn't get in the lift with us, which was odd. When we got in the lift she finally told me "he asked me if I liked white cock". I asked why she didn't tell me when we were waiting next to him. "because you'd have hit him" was her reply. Well yes, obviously.
Going swimming - all the kids gathered round in the changing room shouting "Gai Jin" which is a racist term in itself. Gai Jin is how they refer to non-Japanese but it's usually used for westerners. The term means "other people" but it is a put down really. A better/more polite word for foreigners would be ""Gai koku jin".
There's loads of places that won't even let you in the door if you aren't Japanese. You fuck a Japanese hooker there and the locals find out - they'll avoid that girl from then on.
Saying that - the place is changing but they sure be racist.
Anyway - it was actually an interesting experience, being on the other side of racism.