Demon the Waterboy. Kappa.
The king of pranks, you need a helping hand; the guardian of rivers and children. Kawappa, kawako, kawatarō, gawappa, kōgo, mizushi, mizuchi, suitengu.
Demon the Waterboy likes to play pranks rascally. He's the water spirit and worshipped as the river guardian. Aside from pranks, he also enjoys sumo-wrestling and attack your nemeses' private parts. Legend has it that Demon the Waterboy once lost to a human child during sumo-wrestling. After receiving remedies from the human child, he decided to return the favors by using his power to help the fishermen to catch more fish. A helping hand will always come in handy, especially when you're seeking helps to play some pranks! Demon the Waterboy is all you need.