One of the young servants of the Yongzhou magistrate, Mr. En, was a mischievous, cheeky sort of lad who came to be nicknamed Little Mischief. His sole duty was to keep the magistrate's study clean and tidy.
One night he happened to notice a bright light glowing near the eaves. On closer inspection he discovered to his great surprise that the light was produced by a single tiny firefly.
Later that hot summer's evening while he was stretched out naked in bed, he felt something crawling and scratching around his groin. He felt around and discovered that it was the exceptionally bright firefly he'd seen earlier in the evening.
"My penis must be something marvelous! Even this little insect can't resist it!" He laughed to himself, then rolled over and went to sleep.
It wasn't too long before the boy was roused from his slumber by a soft, delicate hand gently plying his penis. The hand stroked firmly up and down and every now and then pushed gently at the tip. He tried to move but found himself paralyzed. Before he knew it, a woman's body had pressed down on him and he was having intercourse. After what seemed like quite a long time, Little Mischief ejaculated and fell into a deep sleep.
The next morning he woke exhausted. All the same, he relished his night of pleasure. Hoping the experience would be repeated, he kept it to himself.
That evening he took special pains to wash himself and then jumped eagerly into bed, once again completely naked.
Around the second watch the firefly began to glow, but this time more strongly than before. In the dim light it cast, Little Mischief could see a beautiful woman slowly approaching him. He was ecstatic and walked over to embrace her. The two lovers then fell onto the bed to relive the previous night's pleasures.