The 1979 timeline. Kuchisake-onna differs sharply from Edo-period yokai because the whole arc can be traced through newspapers, weekly magazines, and police records: from the early January 26, 1979 Gifu Nichinichi Shimbun "Henshu Yoki" report^[1] to the rapid decline after schools entered summer vacation that August. The prototype was recorded as a rumor from early December 1978 in Shinsei, Motosu District, Gifu: an elderly farm woman supposedly saw Kuchisake-onna near an outhouse away from the main house and collapsed in fear. Shukan Asahi covered the rumor on March 23, then again with a major feature on June 29; Shukan Josei and Josei Jishin followed in July. By June, the rumor had spread from Gifu to Aomori and Kagoshima. In August, when schools and cram schools closed for summer break, the children's oral network was interrupted and the panic faded. This rise and fall, sweeping the nation in months and then vanishing just as quickly, is a signature of modern media-age yokai.

The question-and-attack formula. "Am I pretty?" If the child answers yes, she removes the mask and asks, "Even like this?" If the answer is negative, she attacks with scissors, a knife, a sickle, or a deba kitchen knife. This dialogue became the national core of the legend. Escape methods also multiplied: answer vaguely with "so-so"; say that she is beautiful both outside and inside; chant "pomade" three times, or in some versions six; write pomade on the palm or sole; throw a bottle at her. Later explanations claimed that the surgeon who ruined her face wore too much pomade, and she hated the smell. Other variants say to give her bekko candy, shout "garlic," write the character for dog on the palm, or flee into a building above the second floor because she can only pursue on the ground. Her speed was most often given as one hundred meters in six seconds, though three-second and three-meter-jump variants also circulated. Red beret, red clothing, red high heels, mask, and long hair became standard through newspaper coverage and weekly-magazine features.

Origin theories added after the fact. The Gifu Nichinichi Shimbun^[1] did not give an origin story; it simply reported a rumor among children in Gifu. As the rumor spread, explanations attached themselves to it: failed cosmetic surgery, reflecting the 1970s boom in beauty operations; three sisters whose mouths were all slit, with causes ranging from surgery failure to traffic accident to jealousy; a facial reconstruction from bones found after the Hida River bus crash of August 18, 1968; an escaped patient from a psychiatric hospital in Minokamo, Gifu in 1977-1978; and the resentment of the Gujo uprising of 1754. None of these can be securely traced to primary evidence. They show how a bare rumor grows a past, then stabilizes. Kuchisake-onna's formation is different from Toriyama Sekien's desk-made tsukumogami, built from texts and wordplay, and from local folk beings collected by Yanagita-style folklore. She belongs to the media age.

Edo-period prehistory and the gap between continuity and independence. The theme of a woman whose mouth reaches her ears is older than 1979. The Edo-period collection Kaidan Oi no Tsue^[4] includes a story from Okubo Hyakunin-cho, in today's Shinjuku, where a man with an umbrella speaks to a woman and sees her mouth split to the ears when she turns around; she is said to be a fox in disguise. Similar motifs appear in Ehon Sayo Shigure and Shin Chomonju. A Meiji-period legend from Shigaraki in Shiga tells of a woman named Otsuya who dressed in white, powdered her face, disheveled her hair, set candles on her head, held a sickle, and crossed a pass with a crescent-shaped carrot in her mouth to meet her lover. This is sometimes cited as a model for the 1979 Kuchisake-onna, though primary evidence still needs tracing. Modern folklorists such as Toru Joko^[3] and Yoshiyuki Iikura generally treat the 1979 phenomenon not as a direct continuation of Edo tales, but as an independent postwar event. Edo materials form an older thematic layer; the 1979 legend grows under conditions specific to postwar Japan: cram schools, national magazines, cosmetic-surgery anxieties, and nuclear family life.

Folklore and sociology. Toru Joko's School Ghost Stories (1990)^[3] used field interviews to organize school legends, including Kuchisake-onna, and helped establish modern children's rumor and ghost story as subjects for folklore method. Iikura pointed to cram schools as a transmission channel: they gathered children across school districts before mass media amplified the story. Sociological readings often connect the legend with postwar nuclear families, dual-income households, women's entry into the workforce, and the cosmetic-surgery boom. Anxiety about absent mothers, about beauty, and about the beautiful woman who may have been altered by surgery all gather in Kuchisake-onna. Shigeru Mizuki's Illustrated Encyclopedia of Japanese Yokai (1991)^[5] later included her as a yokai entry, a symbolic moment in which a modern urban apparition entered the yokai framework.

Media afterlives. A monster modeled on Kuchisake-onna appeared in episode 29 of the 1979 tokusatsu series Battle Fever J. In film, Koji Shiraishi's Kuchisake-onna (2007)^[6] is the representative work, confronting the 1979 phenomenon directly as postwar horror cinema. It was followed by Kuchisake-onna 2 (2008), Kuchisake-onna Returns (2012), and Kuchisake-onna in L.A. (2016). The Japan-Korea co-production Ghost Mask: Scar (2019), directed by Takeshi Sone^[7], joins Kuchisake-onna with Korean cosmetic-surgery culture, remaking her across East Asia. In manga, Sho Makura and Takeshi Okano's Hell Teacher Nube chapter "The Terrifying Kuchisake-onna" gives her a sympathetic reinterpretation: Nube exorcises an animal spirit possessing a woman mistaken for a monster and restores her beauty. In Korea, she reappeared in the 2000s as ppalgan maseukeu, the Red Mask, with local blood-type variants. In English, she is widely known as the Slit-Mouthed Woman and appears in introductions to yokai and Japanese modern folklore.

Academic position. Kuchisake-onna is a representative case for the postwar frameworks of modern yokai and urban legend. Around 1988, the Japanese translation of Jan Harold Brunvand's The Vanishing Hitchhiker introduced the concept of urban legend to Japan; soon after, Toru Joko's School Ghost Stories (1990)^[3] brought school legends into folklore fieldwork. From the 2000s onward, sociology, media studies, and cultural studies deepened the analysis, and scholars such as Iikura read her as a model for yokai formation in the mass-media age. Alongside Edo oral yokai, Sekien's bookish tsukumogami, and local beings collected by modern folklore, Kuchisake-onna widened the very idea of what a yokai could be.