Akkorokamui/Atkor Kamuy

Akkorokamui is from Japanese mythology. This creature’s name translates to “string holding kamui,” with string holding referring to its tentacles. It resembles a red octopus measuring 10,000 square meters in size. It was thought to be capable of swallowing ships and even whales in one bite. It was revered as the god of Uchiura Bay and sailors were warned to avoid the water when the sky and sea were red. If you had to be on the water during these times, you had to carry a scythe to protect yourself by cutting the tentacles with it. The origin of this creature is that it was once a giant spider called Yaushikep. As Yaushikep, it loved killing a lot of people, and then people prayed for the figure Repun Kamuy for help. He assisted by making a massive wave to wash Yaushikep into the sea. Once in the sea, it transformed into an octopus.

Citations:

Meyer, Matthew. The Book of the Hakutaku: A Bestiary of Japanese Monsters. United States, Matthew Meyer, 2019.