The Chinatown Tenement is part of The Suspicious-Looking Guy's Shady Past. It is unlocked by finding the test site key.
Before it is unlocked the following text is displayed:
This crumbling tenement building would have been condemned long ago, if people weren't already cramming three families into an apartment. The door was locked, and I assumed it could only be to keep the burglars inside so they wouldn't bother the shopkeepers next door. I shrugged. Didn't have any business in there anyway.
After it has been completed the following text replaces it:
People were emerging from the tenement, blinking in the sunlight. Some of them smiled and waved when they saw me. It felt good to have done something worthwhile, but it didn't change the fact that I needed to get out of town before the yakuza caught up with me.