Encyclopedia Entry:
Aquatic monsters known as “daughters of the sea.” They’re a kind of sea-loving succubus that inhabits the ocean. Women who drown in the ocean and have their bodies completely violated by the magical power of the sea god “Poseidon” are changed into nereids. Normally they are calm like the sea, and free-spirited, but when they have sex with a man they go wild like a stormy sea and indulge in the pleasure.