Wikipedia
Ubume
, a Japanese yōkai, appears in folk stories and literature as an old woman or crone, with a child in her arms, imploring the passerby to hold her infant, only to then disappear. As legend has it, the weight of the child increases by degrees, until the bewitched “child” is revealed to be nothing more than a huge rock or boulder. The first version of this sort of tale was related by Urabe Suyetake, servant of Raiko.