Here is a list of mythical creatures beginning with this letter and I am constantly gathering information from each continent and continually updating.
Amemasu (Ainu)
Amemasu (rain trout) is a giant whale- or fish-like creature from Ainu folklore. Some of the largest amemasu are said to live in Lake Mash? and Lake Shikotsu in Hokkaido, with smaller ones inhabiting lakes throughout northern areas of Honshu. The amemasu are known for capsizing boats, creating earthquakes, and causing other natural disasters.
An amemasu is able to take on a human appearance, usually of a beautiful woman, in order to lure young men to their deaths. The skin of an amemasu is said to be cold and clammy, much like fish skin, which is how they can be identified when they are in human form. The inhabitants of Hokkaido believed that large amemasu held up the Earth. Sometimes, the fish would get tired and this could cause earthquakes, similar to the namazu.