In Japan, some believe in a formless specter called Betobeto-san that follows you around at night. Its wooden sandals make a ‘beto-beto’ sound behind you, but when you turn around, nothing is there, and if you start walking again, the sound continues. However, if you step to the side of the road and say, 'After you, Betobeto-san,’ it will leave you alone. Source Source 2 Source 3