Kappa Bone

Origin
At an unknown point in time, this bone basin was removed from the skull of what was assumed to be a kappa, a Japanese water demon. Wether it truly was or not is unclear, but it's effects are apparent.

Effects
When the bowl is filled with river water and drunk from, the drinker will be able to breathe underwater for a brief time. To maintain the effect, they must pull people underwater and absorb the oxygen from their bodies, drowing the unfortunate victim.

The victim can save themselves by offering a cucumber to the drinker, which will drive them from the area in a panic.