The residents of Chenghai possessed a remarkable ability to transform, able to assume the guise of various beasts when venturing out to forage for sustenance.

A traveler passing through this area sought lodging at an inn. He noticed a congregation of rats burrowing into a large rice vat, refusing to leave despite all his efforts to shoo them away.

Seizing the opportunity while they were pilfering the grain, the guest swiftly covered the vat with a wooden plank and then poured clean water inside. Not long after, all the rats were drowned. Upon closer inspection, he was horrified to discover they were, in fact, the innkeeper's entire family—nearly all perished, save for one son who had miraculously survived, though he was bloated and alarmingly pale.

Enraged by the slaughter of his kin, the son immediately brought the matter before the magistrate. However, the county magistrate, considering the guest's actions to have been unintentional, decided not to press charges.