The is a yà Âkai in the Japanese folklore.
Although in the guise of a small octopus, it is said to expand and envelope boats and people.
The lore is localized in northern Kyoto Prefecture, vaguely described as promontory areas (jutting into Wakasa Bay), though also pinpointed to a village () at the northern tip of .
As the name indicates, is an octopus-like yà Âkai that appear small at first, but expands widely like a piece of clothing when a boat arrives, and sinks both vessel and humans in the sea.
The small octopus can expand to the area of 6 tatami mats, 12 x 12 Japanese feet square, or . Some of them are found concealed inside a shell.
One source ( 1949) identifies the locality of the lore as village, which is on the northern tip of (aka Yosa Peninsula). The localization is given more vaguely as some promontory area in Yosa District, Kyoto., and the yà Âkai is also described as appearing in Wakasa Bay.
An actual marine animal compared to this yà Âkai is the Common blanket octopus (Japanese name: murasaki-dako, 'purple octopus') that inhabits the Sea of Japan. It has membranes between the tentacles when outspread can expand its area 10-fold, though the octopus is quite small. This octopus is in fact called locally in some areas of Japan such as Takeno, Hyà Âgo.ãÂÂ
A similar creature described in a collection of sea yà Âkai is the in the lore of , Aichi Prefecture. It is said to arrive waftingly, encloak its victim in zip, and suffocate it.
Julie Kagawa's novel Night of the Dragon (2020) mentions koromodako, ushi oni and umibà Âzu in the same sentence as creatures one does not wish to encounter at sea.