So out of interest I looked on the internet the setting for Shenmue II when Ryo is in Kowloon. The place Ryo explored in the later half of the game actually no longer exists. The Chinese government tore the whole place down in the early 90's because it was not only disgusting, but it was an eyesore filled with crime and black market dentistry, medical, and anything illegal under the sun really. It was known as the Kowloon Walled City. There was no easy way to get into it other than some dark tunnels. Jackie Chan actually shot a scene for Crime Story in Kowloon and the explosions were real because the government had no problem in destroying the buildings. Shenmue actually made it look better than it actually was.
Here is the video from Crime Story at Kowloon.http://www.youtube.com/watch?v=5H9tjc_EAfo
Here is an 80's movie talking about Kowloon and going through the tunnels.http://www.youtube.com/watch?v=KEo6ogAnoZ8
Here is an undercover video of Kowloon.http://www.youtube.com/watch?v=OSnvqBhWUOc
And here are some pics.
Of course, here is how Kowloon is depicted in Shenmue IIhttp://www.youtube.com/watch?v=ffd8nNqNz2A
And Lastly, here is the Wikipedia article on this place.http://en.wikipedia.org/wiki/Kowloon_Walled_City