They been got all their swag and musical talent from the US.
All of the legends like Micheal Jackson, Prince, Stevie Wonder, etc. SOLD OUT in Japan. They loved our music, so many entertainers and labels looked at Japan as the #1 music market in Asia.
Funny historical tidbit - they actually got hip to black music during the 70s because they sold a lot of the musical equipment to places like NY and regularly had to go out there to service them. So they always got new music coming out from the US, the whole disco/soul/house music shyt they were one of the first to hear about.
Before I believe they fukked with Jazz and shyt but I don’t know the history about that too much.