There is a town and pond in Ibaraki called Ushiku, with a local tale behind them that explains how the town got its name(see a photo of the pond at http://www.tripadvisor.ca/LocationPhotoDirectLink-g1021208-d1675091-i36468629-Ushikunuma_Pond-Ryugasaki_Ibaraki_Prefecture_Kanto.html). As the story goes…
“… a local monk had become so lazy he turned into a cow. Mortified, he decided to drown himself in the pond. The chief priest tried to stop him by grabbing onto his tail,, but the tail came off and the water swallowed his ponderous body. Since then, the pond has been called “ushiku-numa,” meaning cow-swallowing pond.”
Source: Beauty where ‘there’s nothing to see’, the Yomiuri Shimbun, Feb 2, 2014
Another source adds a few details to the tale:
“There is an old Japanese saying that goes like this: “If you lie down right after you eat, you will become a cow.” There is a legend at the origin of this saying. There once lived a lazy and greedy monk. Despite warnings from his superior, he continued to laze around and pass his day away just eating. One day he turned into a cow. He became so despondent that he threw himself into the pond in front of his superior, who tried to stop him. From then the pond came to be known as the Ushiku Pond, the pond that ate (ku) the cow (ushi).
The pond is a quiet expanse of water with a peaceful shoreline path, and the Ushiku area is said to be home to frollicking kappa, mythical water-dwelling creatures.
A Kappa Folktale (a kappa is a legendary froglike creature)
The Ushiku Pond is suited for swimming and many children go there to play. According to the legend, a mischievous kappa (legendary frog-like creature) pulled the children into the water and drowned many of them. Infuriated by the incident, the townspeople decided to take revenge. They caught the creature sleeping by the pond and tied him to a nearby pine tree. He begged for mercy and the townspeople let him go. After this incident, he never again pulled a child into the pond. — source: Ryugasaki http://hometown.infocreate.co.jp/en/kanto/ryugasaki/denset-e.html
See photos of the Ushiku Pond and read more: In Tsukuba, there is a Ushiku Pond and an Ushiku shrine dedicated to the pond deity http://www.alientimes.org/Main/UshikuPond