Ksitigarbha Bodhisattva is the Earth Store Buddha.
Originally a young Indian girl of the Brahmin caste. Due to her impiety, her mother suffered in hell after death. Concern for her mother led the young girl to make a great vow to save all beings from such torments. Thus, Ksitigarbha represents filial piety, the respect and honor for one's parents such that one chants the Sutra of Filial Piety.
IMHO this sutra shows that even a human being or a demon king will be reborn as bodhisattvas when they practiced merit transference as the Brahmin girl did after her mother's death.