塗壁 Little is known about the true appearance of nurikabe because these yokai are usually said to be invisible. During the Edo period, however, artists began to illustrate this creature, giving it an appearance somewhere between a grotesque, fantastic beast and a flat, white wall. Modern representations of the nurikabe depict it as a plain, gray, bipedal wall with vague face-like features. Nurikabe appear mysteriously on roads late at night. As a traveler is walking, right before his or her eyes, an enormous, invisible wall materializes and blocks the way. There is no way to slip around this yokai; it extends itself as far as to the left and right as one might try to go. There is no way over it either, nor can it be knocked down. However, it is said that if one taps it near the ground with a stick, it will vanish, allowing the traveler to continue on his or her way. The true nature of the nurikabe is surrounded in mystery. Based on its name, it seems to be related to other household spirits known as tsukimogami. It has also been suggested that the nurikabe is simply another manifestation of a shape-shifting itachi or tanuki. Mischievous tanuki are said to enlarge their magical scrotums into an invisible wall in order to play pranks on unsuspecting humans.