Kappa are mythical creatures from Japanese folklore, often depicted as humanoid beings with a dish-like depression on their heads that holds water, which is essential to their life force. They are known to inhabit rivers and ponds, and are said to be mischievous, sometimes luring humans into the water or challenging them to wrestling matches. Despite their trickster nature, Kappa can also be helpful and are believed to possess knowledge of medicine and healing. They are often portrayed as both dangerous and benevolent, making them complex figures in Japanese culture, with stories that have been passed down through generations.