Umi-bōzu by Shigeru Mizuki.
‘Umi-bōzu are giant black bulbous beings that live in the sea. Sometimes they have glowing eyes and a beak, and other times they have no facial features at all. To survive an umi-bōzu encounter at sea, one should remain quiet and look in the opposite direction. Speaking or looking at the creature may send it into a rage — and that usually ends in tragedy.’