Ksitigarbha (Di Zang in Chinese; Sai Nyingpo in Tibetan; Jizo in Japanese) Bodhisattva's name means the "essence of Earth."  He vows to enter nirvana only when Hell is empty of sinners' souls.  Until that time comes, He labors to help all beings attain enlightenment.  He appears in many forms (e.g., deity, monk, layman, dragon, etc.) depending on the beings which He is helping.  He is often depicted as a monk holding a staff with his right hand and a pearl in his left.  Among his attendants are the Ten Lords of Hell.  They render judgments and pass sentences on the deceased.  Depending on decease's crimes and meritorious deeds while alive, they are put on the paths to heaven, spirit realms, hell, etc.
 

	Source: DiZongDian

The Sutra of Ksitigarbha's Original Vows contains several chapters about the deeds of Ksitigarbha Bodhisattva in his previous incarnations.  In one previous incarnation as a "blessed brahman woman," she attempted to find out her mother's fate and ease her mother's suffering in the after-life by making great offerings in the temple of a celestial buddha.  She knew that her mother's heart held deviant views and desecrated the "Three Jewels."  She prayed fervently in the temple, and her sincerity moved the celestial buddha.  The celestial buddha spoke to her through a voice from the sky instructing her to recite the celestial buddha's name for a period of one day.  Upon completion, her wish to find out about her mother's whereabouts would be granted.  She retreated to her quarters and begin chanting.  After reciting the celestial buddha's name for one day, the holy woman suddenly found herself standing on the beach of a boiling sea filled with sinners' souls.  There were iron beasts diving from the sky and running on the sea.  These beasts were chasing after the sinners' souls and eating them.  There were other grotesque beings (some with many eyes and arms, some with many heads and feet, etc.) herding the sinners' souls toward these iron beasts.  Despite the disturbing carnage around her,  the holy woman's heart was calm because of the power generated by concentrating on the name of the celestial buddha..

A ghost king name "No Poison" approached her and paid his respect.  The ghost king inquired why was she there.  The holy woman inquired "Where am I?"  The ghost king told her: This is first great sea to the west of 'Iron Surrounding Mountain'.  She asked:  Is it true that hell is inside the 'Iron Surrounding Mountain'?  The ghost king replied, "Hell is truly in there."  Next, the holy woman asked how did she enter into this realm.  The ghost king answered that there are only two ways to enter hell:  Pulled into hell by the accumulation of negative karmas (power of the negative karmas) or Protective transport as result of a god exercising divine power (power of the gods)."
 

The holy woman further inquired, "Why is this sea boiling and filled with souls?" The ghost king replied, The souls in this sea are sinners who had died recently.  They had not done meritorious deeds while alive, and their living relatives did not transfer good merits to these souls during the first 49 days after their deaths to alleviate their punishment.  The negative karmas of these souls are now drawing them toward specific regions of hell where they will taste the bitter fruits beared by their past evil deeds.   So, they must first cross this great sea. After drifting for two hundred thousand kilometers, they will enter another great sea to the east of this sea.  The suffering in that great sea is twice of the sufferings that you see here.  There is yet another sea to the east of the second sea.  The suffering in this third sea is four times of the suffering here.  These three seas correspond to the three types of ill karmas, and these three seas are known collective the "Seas of Ill-karma."  The holy woman asked, "Where is hell?"  The ghost king responded, "Hell is located beyond the 'Seas of Ill-karma'.  The hells number into the thousands.  Each are different.  There are eighteen major hells.  Then, there are 500 secondary hells which inflict boundless amount of suffering.  Additionally, there are thousands of minor hells which also inflict immeasurable suffering.

She asked the ghost king, "My mother had died recently.  I want to know which hell did her soul enter?"  The ghost king asked, "Please tell me your mother's deeds while she was alive?"  The holy woman replied, "My mother's heart had been poisoned by evil.  Sometimes, she would pay respect to the 'three jewels'.  Often, she would reject the dharma and desecrate the 'three jewels'."  The ghost king inquired further, "What is your mother's name?"  The holy woman replied, "Her name is 'Yuedili'."  The ghost king responded, "Please return home.  Your mother had been set free and granted entrance into heaven by a celestial buddha three days ago because of her daughter's great offerings and pious prayers in the temple.  Many other sinners also benefited as the buddha also liberated them."  Upon answering this question, the ghost king paid his respect and left.

Then, the holy woman found herself in her quarter as if she had awaken from a dream.  Knowing her wish had been granted, she returned to the celestial buddha's temple and swore an oath.  In my future lives may I assist sinners by providing convenient methods for attaining liberation.

Source: Univ of Illinois BSG	Ksitigarbha Bodhisattva is known as Jizo in Japan.  His statues are extremely popular over there.

In another previous incarnation, Ksitigarbha was a king who wanted to awaken his people.  He wanted to stop committing sins.  In a discussion with a friend, the friend believe the best way was to become a buddha to lead the people out of their ignorance.  The friend vowed to become a buddha.  While Ksitigarbha thought it would be best to alleviate the sufferings of his people as a bodhisattva and slowly move them into enlightenment.

The Ksitigarbha's Original Vows Sutra instructs the reader to place an image of Ksitigarbha Bodhisattva in the buddhist shrine and recite this Sutra three seven times in front of the shrine.  This would alleviate the suffering of reader's relatives who had fallen into hell (one may also ask others to recite for you and transfer the merit to the decease).  The decease's sentences would be shortened or they will be released from hell, depending upon the amount and type of bad karma the deceased had accumulated.

This Sutra also instructs that the period of the first forty-nine days immediately after a person had died is extremely important.  The 49th day is when the final judgment for the decease is entered and sentence passed out.  Any merits generated by the decease's relatives during this 49 days period can be transferred to the decease to lessen any punishment or increase the decease's blessing.  Some meritorious deeds are building temples, making donation to the poor, building roads, provide free copies of holy books to people, etc.  One-Seventh of the merits would be transferred to the decease, six-seventh of the merits would be accumulated by the patron.

Ksitigarbha was designated by Shakyamuni Buddha to be the guardian of Buddhism on Earth during the period from Shakyamuni Buddha entering Nirvana until the arrival of Maitreya, the Buddha of the future.