Always interesting to see all the mythological "weird but maybe-possibly harmless gremlins" people came up with in the pastThe akaname (垢(あか)嘗(なめ), 'scum-licker'; 'filth-licker') is a Japanese yōkai depicted in Toriyama Sekien's 1776 book Gazu Hyakki Yagyō, with its precursor or equivalent akaneburi (/垢ねぶり/垢舐(ねぶり)) documented earlier in 1686.
These beings presumably lick the filth and scum that collect in bathtubs and bathrooms.