Kokon Chomonjuu (1254)
A monk by the name of Futodamaou spent much of his time in the arms of a dancing woman, and went to visit her often. His wife was an extremely jealous woman, and night and day she wondered what to do with him. It drove her mad, and yet the monk cared not, nor did he stop his visits.
On the second day of the second month of the sixth year of the Kenchou era, the monk once more spent the night at his lover’s place. They lay in the same bed, and as the monk climbed on top of the woman for some fun, it somehow felt like he was sleeping with his wife rather than his lover.
‘Hmm? That’s strange,’ he thought and drew back, but it was most definitely his lover beneath him. He climbed on top of her once more, but again it felt just like his wife.
Chills ran down his spine and he got off the woman. He didn’t know where from, but suddenly a six foot long snake slithered towards him and clamped onto the tip of his manhood.
He tried to shake it off, but the snake bit down harder. He feared that even if the snake were dead, it would not let go. The monk blindly grabbed for his sword and cut the snake’s mouth open.
The snake died shortly thereafter. The monk’s manhood swelled, and both his mind and body fell ill, the monk becoming a shell of his former self. The snake’s corpse was tossed into a canal, and curious onlookers from all about Kyoto came to see it.
I don’t know whether it’s true or not, but they say that that very same night, the monk’s wife took ill and soon died as well.