Gaki

Gaki (Japanese: 餓鬼 or がき, meaning "hungry ghost") or Preta are suffering spirits from Buddhist cosmology. They will try to eat anything, but are never able to find nourishment.

Myths & Legends
Gaki are eternally hungry and thirsty. There are many kinds of gaki, each of which suffers in a different way related to the sins he or she committed in a past life. Some are unable to eat or drink anything at all. Whenever they try to eat, the food instantly bursts into flames and vanishes. These gaki are only able to eat food which has been specially blessed for them in Buddhist services. Some gaki are able to eat only unclean things, such as feces, vomit, corpses, and so on. Others have no trouble eating anything they please. However, no matter how much they wolf down, their hunger and thirst are never sated.

Appearance
Gaki are spirits which live in horrible torment and are afflicted with constant suffering. They look vaguely human, but they have distended, bulging bellies and tiny, inefficient mouths and throats. They inhabit a parallel realm called Gakidō. It is a barren place, full of deserts, wastelands, and other inhospitable terrain.

A Charitable Festival
In some Buddhist traditions, a special ceremony called  segaki  is performed during the Obon season, to help ease the suffering of the gaki. In this ceremony, offerings of rice and water are laid out on special altars, out of sight of any statues of the gods or Buddha. The gaki are called to come and eat, while prayers are said to ease some of their suffering.

Origin
The realm of the gaki is considered one of the four “unhappy” rebirths. In the cosmology of birth and rebirth, the realm of the gaki is only one step above the realm of Jigoku — the main difference between the inhabitants of Jigoku and the gaki being that those in Jigoku are confined to their prison. Gaki may roam free as they suffer.

Today, the word gaki is also a very nasty term for a child. This comes from the perception of children always wanting more food and never feeling satisfied with what they get.