I've never seen a story proper, but I've seen it as an explanation of the festival a few times. [Kanamara-Matsuri: Festival of the Steel Phallus](https://zoomingjapan.com/travel/kanamara-matsuri/) "The festival dates back to the Edo period (1603-1867). There is a famous legend among locals that explains the origins of the “Kanamara Matsuri”: Once there was a sharp-toothed demon who fell in love with a beautiful young woman. She wasn’t interested in the demon and when she decided to marry another man, the demon became very jealous. He inhabited her vagina the night before the wedding. That way the demon bit off the penis of two of her husbands. Everybody in the village was upset and so finally a blacksmith forged a steel phallus. With that they tricked the demon. His teeth were broken and he left the girl’s vagina. This eventually led to the enshrinement of the iron phallus and the Kanamara Matsuri."