Ureshii, that's so interesting...I didn't realize they have specially designed clothes for that purpose. I always felt bad for the local kids running around in 4-6 thick layers in 30 degree temps and sweating and red faced.
My pediatrician told me when my son was born to dress him in one layer more than I felt comfortable wearing while an infant and then let him decide how many layers to put on once he is old enough to make those choices (between 2-4, depending on the developing maturity of a child). The locals must think horrible thoughts as my son runs around in nothing but a t-shirt in 25 degree temps. (they must really think I'm awful for dressing my newborn in only 3 layers....but they think I'm awful for a variety of reasons, such as carrying my baby in a sling etc, so I guess I'm hopeless...) I carry an extra layer in case he asks for it, but I don't make him wear anything he doesn't feel comfy in.
But I agree with thanka; air-con makes extra layers absolutely necessary. Even in this weeks freezing weather, locals have all the windows wide open as if its a warm spring day. Extra layers are necessary to carry along!