(AAAAH I almost forgot to upload this!)

The Umi bozu doesn't necessarily look like this, this is just me being creative.

It is one of the most mysterious yokai of the seas. No one knows what it looks like, because it is only ever shown from the shoulders up.

Usually you won't even know that you'll come across one because the day will be bright and clear, but within a few moments the sky will turn dark, the rain will fall, the sea will become wild, and a large humanoid figure will come out of the depths. It is pitch black with large round eyes, and is only seen from the shoulders up. Some say the body is serpentine, others say it is humanoid.

No matter what it looks like, it will then commence to tear your ship apart, or they will just smash the hull apart. Occasionally they will ask for a barrel from the crew, and upon being given one will use it to pour water onto the deck and drown the ship. As a little word of advice, give them a barrel with no bottom.