You were a fisherman around the island of Kyūshū, you were young and were fishing to get some money to get yourself your own house, you then heard a woman screaming, holding something that looked like a baby, you walked to her as she sighed in relief.

''Could you hold my child? I need to do something important, I can't let it get harmed.''

You nod, not thinking twice, and take the baby as it was... a rock... it fell on your foot, making you stuck a bit, you look at the woman, confused, as she was no longer a worried mother, she was a vampiric sea serpent with a woman's top. You now realize it was a Nure onna

''You fool.'' she said with a smile as her face was a bit covered by her long black hair