The stories of a terrifying sea monster lurking in the waters off the coast of Japan are a rich and ancient part of Japanese folklore. These captivating legends, whispered among sailors and coastal communities for centuries, are often attributed to two main types of mythological creatures: the Umibōzu and the Ryūjin.

The most famous of these is the Umibōzu, which translates to “sea priest.” Legends describe it as a gigantic, black, humanoid figure that emerges from the depths and either capsizes ships or demands a barrel from the crew. If a barrel is given, the creature scoops up seawater and drowns the sailors. The stories of the Umibōzu are likely rooted in the very real and unpredictable dangers of the sea around Japan, where sudden storms, typhoons, and rogue waves have a long history of claiming ships without a trace.

Another powerful figure in Japanese mythology is Ryūjin, the dragon god of the sea, who lives in an underwater palace and controls the tides. While not a monster in the terrifying sense, his immense power and the awe he inspired in ancient mariners speak to the deep respect and fear the sea commanded. These myths were likely inspired by real-world sightings of giant, elusive creatures. For centuries, the existence of the giant squid was a myth, but it has since been scientifically proven. Sightings of these massive creatures or other long, deep-sea fish like the oarfish may have fueled stories of sea serpents and dragons, blurring the line between fact and folklore.