East Asians including Chinese, Japanese and Korean when exposed to long duration of sunlight can get very dark. A person can go back and forth from as pale as Nordic Europeans to as dark as Indonesian in months. The reason you don't see many is that beauty preference in those societies is very light skin. It's a class bias beauty standard as until recently dark skin implies a person is an outdoor manual labor of the lower class. It's rare in Japan and Korea nowadays because these are post industrial economies and the only people who are super tanned are by choice against society norm. Japanese brown skin tomboy hentai is a kind of rebel fetish along the line of goth porn.