Miko is basically the girl who works or helps around the shrine like in Japan. What makes this girl standout is the costume she wears. Well, it’s a kind of attraction for people to come to those shrines especially if cute girls wearing in miko outfit. So what does a Miko do? In modern days, they’re usually helping around the shrine (obviously) like cleaning, perform ceremonial dances during special days, fortune telling (called omikuji and quite popular) and others. Usually for a harem-like anime, there shall be at least one character who is devoted to the shrine either willingly or due to family matters, in which, the latter is the most chosen reason for them to be one. It’s a popular choice too for author to create a Miko character in visual novels and eroge. There’s like a forte for someone to wear hakama, the kind of miko clothing. There are various of hakama like the ones being worn by students at a dojo or even during social events. But for a Miko, it’s usually white robe with red hakama.
Hmm, gonna close this off with a Scary Armpit picture.