You need to go to hipster stores. American Eagle, Hollister, etc. They typically carry more smaller, tighter fit clothing not meant for fat people. My brother just ordered a shirt from Korea, it was a Korean size L or XL, which is actually equivalent to a M in U.S. size. Not sure about the quality, but I will find out soon enough. I believe the place he orders from is youstars.
Also, you can try the kids section at stores. I was a target, looking for pants in the mens section, and I randomly found some pants that did not seem to belong there. I tried them on and they fit me perfectly. Turns out it was a kid's size.
Not asian, but I am of a smaller size and frame.