The yokai whose turned face is an old man
Iyami
The boy calls to a back like his sister's. When it turns, the face is a leering old man. The basket falls, rice scatters, and only crying remains.
Overview
Iyami looks like a beautiful young woman from behind. When someone calls out and sees the front, the face is that of a wrinkled old man. It startles people by overturning what they expected.
Encounter
In Sendai at dusk, a traveler sees a woman walking ahead. The back resembles someone familiar, but when she turns, the face is entirely an old man. Similar tales are also told in western Japan.
Lore
Iyami is linked to Toriyama Sekien's Iyaya in Konjaku Hyakki Shui, a figure whose back is beautiful but whose reflected face is old. The name draws on a Chinese anecdote about naming an insect kaiya.
Traits
It takes the rear view of a young woman and betrays the viewer's expectation with one turn of the face. It has no claws or fangs; the shock of recognition is its real technique.
Long ago, Dongfang Shuo saw a strange insect and named it Kaiya; this Iyaya must be named after that example.
Toriyama Sekien, Konjaku Hyakki Shui