Yokai Attack the Japanese Monster Survival Guide by Tatsuya Marina

There's one by the name of Umi Bozu, they're known as the sea monks. Japanese Yokai said to resemble great black, bull-black beings with glowing eyes emerging from the water. Also depending on the account, they might be vengeful ghosts of the sea. And in this they have much in common with some Chinese ghost traditions, the boat spirits or fune jure.