I do remember seeing two young girls begging alone on a subway train. They were obviously sisters. The older was maybe nine or ten and other about six years old. They were both dressed in dirty clothes and unwashed, which is extraordinary for the usually immaculate Koreans. But this was the exception, not the rule.
Beggars have a different style than in the west.
Usually they don't say anything. If they have any physical injury, they display it. Usually they try to make themselves look as pathetic as possible. Some will walk into businesses or into restaurants or coffee shops. Again, they won't say anything.