This Japanese urban legend is called “No Face” and is about Nopperabou, a creature from Japanese folklore.
Though the No Face is able to appear to others like a normal person, this is just an illusion. The Nopperabou really lacks eyes, a nose or a mouth. Instead of normal human features, nopperabou have only smooth skin. People who encounter nopperabou usually do not immediately realize that they are talking to something that is otherworldly, as the creatures are able to create the illusion that they have a normal human face.
A nopperabou will wait for the right moment before causing their features to disappear, scaring the person they are speaking with. People usually run into nopperabou at night in lonely rural settings, although they can appear anywhere as long as the area is deserted. The nopperabou’s primary purpose is to scare humans, but beyond that they do not seem to have any sort of agenda.
One famous nopperabou story is Lafcadio Hearn’s Mujina. The story is short and deftly describes an encounter with a nopperabou, but it is also the source of much confusion. In the story, Hearn refers to the creatures as mujina, which is actually a different type of creature altogether (a sort of badger). This mistake has caused a lot of Western readers to mix up the names for nopperabou and mujina, and even today you will run across authors and scholars that are using the wrong name. Regardless, the story itself is a very typical tale of nopperabou mischief.