She asks her victim: "Am I beautiful?". Whether the victim says "Yes" or "No", she'll slit his/her mouth. The only way to "destroy" her is saying "No, you are ugly, and I don't wanna be like you!". Momoko did that, and Kuchisake-onna became trapped on a lipstick.
Kuchisake-onna also appears as one of the main Ghost Hosts in the second season Gakkou no Kaidan SP, although she is somewhat different and less evil.
- Kuchisake-onna was based on a Japanese urban legend of the same name, that became very popular in Japan in the 90s. There is even a series of movies about this legend. For more information, see Carved.