fake crooked incisors ("yaeba") inserted by clinics in Tokyo. These teeth look a little like fangs, though not so prominent as those sported by the fashion poster girl in the above photo.
What is the attraction of crooked teeth and fangs? The attraction of crooked teeth is in part a gesture at natural rustic charm, such as gypsy look cosmetics, or stone washed, pre-ripped jeans. By their imperfection they give the impression of honesty. But why incisors? Why women? And why fangs?
I think that the logic goes something like this.
Subconsciously the Japanese know that their women are at base, from time immemorial (think Izanami), just plain scary. They are taught, or preprogrammed to believe that babies are their prime objective and to rear them they'll turn you into a "salary man," or basically eat you alive.
Japanese women are required therefore, to go to great lengths to hide their 'true nature'. If they are to be perceived as attractive they must never grow up. Above all they are required to be cute, or rather wallow in cute. But they'd be even scarier if they hid their desires completely. So, when their scariness is showing a little bit, then they are even more cute.
Cute Japanese women with fangs are like Western gentlemen with a bit of chest hair or stubble showing (or like a handsome werewolf with a thick beard, inset bottom right) in all cases they hint that in fact they do still have bite.