Ungaikyō

Sekiken depicts a mirror[1] with a face standing behind a slanting column and a tongue protruding from it, which is described in the side notes in Gazu Hyakki Tsurezure Bukuro as follows.

The reading-book (yomihon) Ehon Sangoku Yofuden by Takai Ranzan notes it to have revealed the true identity of the beautiful woman Daji who corrupted the Shang emperor King Zhou.

[3] The ungaikyō in Gazu Hyakki Tsurezure Bukuro is noted to be an original creation of Sekien Toriyama based on the shomakyo,[4][5] and the accompanying picture shows it to be a mirror with a monstrous and mysterious face floating on it,[6] as can be seen in the figure.

[6] The name “ungaikyo” is noted to possibly be a reference to the Chinese geography book Shanhai Jing Classic of Mountains and Seas, which describes a number of yokai.

[7] In a book written by yokai manga artist Shigeru Mizuki, there is a legend that on the fifteenth night of the eighth month (Hazuki) of the lunar calendar, a crystal tray is filled with water under the moonlight, and when the water is used to draw the image of a yōkai on the mirror's surface, that yōkai will then dwell inside the mirror.