According to him, many of the Korean residents of Seoul were convinced that there were Japanese ghosts haunting the streets of Seoul. For some reason the people called them "Yobosang," a derogatory name for Koreans used by the Japanese during that period, and believed that Korean women were especially susceptible to these ghosts. At night, if a woman had to go out into the streets, she carefully packed a packet of ground red pepper and placed it in the roomy sleeves of her jacket to be used as a weapon against the Japanese ghost. According to the local belief, the ghosts could not endure the fiery taste of the red pepper.
Mr. Neff has written about ghosts before; here's another article. The Marmot's Hole post in question seems to be this one, which has plenty more tales of hauntings in Korea. A recurring theme seems to be to avoid apartments and houses with cheap rents, because something very grisly happened there.
There are a couple more experiences with Korean ghosts recounted here and here. From what I've read on Dave's, the "sitting ghost," or sleep paralysis, seems to strike with some frequency over here, sometimes accompanied with an apparition of a demonic-looking old woman. Even my girlfriend has encountered something like this, but she wisely kept her eyes closed.
In addition to my fear of spiders, I'm also very afraid of ghosts, so if you have any ghost stories, feel free to keep them to yourself. My coworkers were not as obliging, and told me about a haunted house in Suncheon that was featured on a TV program a few years' back. They didn't remember where it was, and poking around the internet didn't turn up anything.
Not necessarily related to Halloween, but one story that my students were very afraid of a few years ago had to do with the "red mask lady." Apparently, and this is based off what I've read from other foreigners and on the testimony of ten-year-olds, a woman suffered a mishap during cosmetic surgery leaving her with a "Glasgow grin" similar to Heath Ledger's Joker. She---whether still alive or as a ghost, I don't know---would wander around at night with a SARS mask asking children who happened to be out "do you think I'm beautiful?" If you said "no," she would take off her mask and abduct you. The story is a little muddled here because I heard that if you said "yes" she would say "what about now?" and take off her mask and kill you or abduct you or whatever. There's another account of her here. A Naver search will turn up some books and pictures on the topic. It also turns up a Japanese movie from 2007 whose profile is protected by an age-verification screen. A few pictures below, and a rather unpleasant one here from the movie, 나고야 살인사건.
Wikipedia has more on the original Japanese version of the urban legend:
The legend is said to originate with a young woman who lived hundreds of years ago (some versions of the legend state the Heian period) and was either the wife or concubine of a samurai. She is said to have been very beautiful but also very vain, and possibly cheating on her husband. The samurai, extremely jealous and feeling cuckolded, attacked her and slit her mouth from ear to ear, screaming "Who will think you're beautiful now?"
The urban legend picks up from this point, stating that a woman roams around at night (especially during foggy evenings), with her face covered by a surgical mask, which would not be especially unusual, as people with colds often wear masks for the sake of others in Japan. When she encounters someone (primarily children or college students), she will shyly ask, "Am I beautiful?" ("Watashi kirei?"). If the person answers yes, she will take off her mask and say, "Even like this?" At this point, if the victim answers "No," she will slay them (in many versions, her weapon is a pair of scissors). If the victim tells her she is pretty a second time, she follows the victim home and slays them in their own doorway, due to the fact that "kirei" (きれい), Japanese for 'pretty,' is a near homophone of "kire" (切れ), the imperative form of "to cut". In other versions of the myth if you reply yes again she will give you a large blood soaked ruby and walk away.
During the seventies, the urban legend went that if the victim answers "You're average", they are saved. When the urban legend was revived around 2000, the answer that would save you was changed to "so-so," with the change that this answer causes the kuchisake-onna to think about what to do, and her victim can escape while she is in thought.