The slit-mouth woman originating from the Edo period of Japan, she is the vengeful ghost of a woman who was mutilated and killed by her jealous husband. She would appear to people walking alone at night and uncover her face before asking them if she is beautiful. If they answered 'yes', she would kill them with a pair of shears she carries. If they answer 'no' she will call them a liar and kill them anyway. There is a way of escaping alive but as with most urban legends, it varies depending on the version of the story: if someone says 'so-so' or 'how about me?' she becomes confused long enough for the person to flee.
It is particularly difficult to get a Spell Card from Kuchisake-Onna through demon contact because almost every contact makes her angry. This mirrors her behaviour from her legend, when she will most likely kill the person she encounters whatever they may say. However, she tends to be happy when hearing Kei's sarcasm, and eager when receiving gifts of items and money.
After the blimp scene, the player may encounter Kuchisake-onna if Tatsuya talks to the old man near Mt. Iwato and then spreads the rumor that he tells him. Afterwards, she will appear once as a random encounter and drops Kuchisake-onna's Mask, which can be traded to the rumor-giver for a Megido Card. After trading the mask, the rumor-giver mentions that the Kuchisake-onna would mumble to itself a lot, saying "I wonder if this costume's too obvious..." and "Has Tatsuya-kun reached the detective agency yet?".