Gaki is the Japanese name for the preta, a being found across Hinduism, Buddhism, Taoism, and Chinese folk religion; the characters 餓鬼 mean "hungry ghost." In Buddhism it is one of the six states of rebirth, a condition shaped by the karma of greed.
It is depicted with a grotesquely swollen belly but a neck so slender it cannot properly swallow, tormented by endless hunger and thirst. Its very lack, never to be filled, is the punishment.