Nurikabe
The nurikabe (塗り壁 or 塗壁) is a "yōkai", or spirit, from Japanese folklore. Its name translates to "plaster wall", and it is said to manifest as an invisible wall that impedes or misdirects travelers walking at night. Sometimes referred to in English as "The Wall" or "Mr. Wall", this "yōkai" is described as quite tall, to prevent people from climbing over it, and wide enough to dampen any attempts to go around it. Japanese scholar and folklorist Kunio Yanagita recorded perhaps the most prominent early example of "nurikabe" and other "yōkai" in his books. Manga artist Mizuki Shigeru claims  to have encountered a "nurikabe" in New Guinea, inspiring a "nurikabe" character in his manga "Gegege no Kitarō." Mythology. The "nurikabe" takes form as a wall—usually invisible—that blocks the path of travelers as they're walking. With the exception of Mizuki Shigeru's experience in New Guinea, most legends and accounts of "nurikabe" come from Kyūshū, in the Ōita and Fukuoka prefectures. Some iterations of the legend say that trying to go around the wall is futile as it extends forever. Others say that knocking on the bottom left part of the wall with a stick will make  it disappear, but that knocking on the upper part of it will yield no result. It has been suggested that the legend of the "nurikabe" was created to explain travelers losing their bearings on long journeys. Some "nurikabe-"like experiences that have been recorded have been attributed as the doing of "tanuki," known as "tanuki no nurikabe". These happenings, instead of involving a wall, are instances where the traveler suddenly cannot see in front of themselves. In popular culture. The "nurikabe" has been explicitly referenced in several forms of pop culture. There is a "nurikabe" character named Nurikabe in Mizuki  Shigeru's manga series "Gegege no Kitarō". The character's main function is to be a shield in order to protect other members of the Kitarō family. Mizuki attributes much of his inspiration for the series to an experience he had with a "nurikabe" in New Guinea during World War II, as well as to the writings of Kunio Yanagita. Mizuki's illustration for the "nurikabe" gave it a more physical and anthropomorphic form with arms and legs, rather than the more traditional invisible wall concept. "Nurikabe" is brought up in the first volume of Bakemonogatari written by Nisio Isin . In the video game series "Yo-kai Watch", there is a "nurikabe" character called Noway who looks like much like Mizuki's wall with arms and legs. Noway's Japanese name in the series is "murikabe" (ムリカベ), a portmanteau of "nurikabe" and the word "muri" (無理), meaning "No way!" or "Impossible!" in colloquial Japanese. The character has appeared in other adaptations of the series, including an anime and manga of the same name. In the video game "Nioh", "nurikabe" act as secret walls, blocking off optional hidden paths. In the light novel series by Kou Kimura Petopeto-san (ぺとぺとさん), later  adapted to anime, a Japanese school has special students (officially known as "students from specified races") based on yōkai from Japanese mythology; one of them is a nurikabe. There is a logic puzzle called Nurikabe, wherein boxes are filled in around numbers to create walls, thus forming "islands" corresponding to the numbers. References. 妖怪ドットコム 『図説 妖怪辞典』 幻冬舎コミックス、2008年。。