Before you get too riled up: that’s not really her bum. This is a Japanese product that’s on the market. The skirt has a picture of a bum printed on it.
I found this on David Galbraith’s site. Sometimes what Koreans say about Japan goes too far, but sometimes I have to agree and say something very weird and vaguely sinister is going on over there in Tokyo. Certainly not all bad, but… kind of… well, hmmm.