Considered to be the wife of a samurai warrior who slit open her mouth when he found about her infidelity, Kuchisake Onna has an interesting urban legend surrounding her. She walks on the streets after sunset on foggy days with her face covered with a surgical mask, approaching travellers. She then asks the travellers if they thought she was pretty, as most would answer with a "Yes" she will then remove her mask exposing her slit mouth.
She would ask the traveller again is they thought she was pretty. If they answered with a "Yes" again she produces a pair of scissors and slits their mouth open. If they say "No" she will then produce a scythe and cut them in half. Apparently the trick is to answer saying that she looked average, which would confuse her, and she would then leave.
