Da'ath (from Hebrew: inteligence, thinking, knowledge) is only mentioned verbally in Guilty Crown. It supposedly caused the meteor crystal containing the Apocalypse Virus to strike Earth, and is ultimately responsible for the corruption, death (Guilty Crown: Lost Christmas), and reincarnation of Mana Ouma through Inori Yuzuriha. It seems to want to restart the human race, by eradicating the human race with the Apocalypse Virus, save for Mana and her chosen Adam, the person she chooses to marry. Da'ath acts through an envoy, known as Yuu.
In "Lost Christmas", it was revealed that Da'ath is a secret organization that has long since been established from an ancient era, monitoring humans evolution and extermination. Scrooge has a hatred against Da'ath for using him as an experiment in their research facility.
The organization is similar to the concept of SEELE from Neon Genesis Evangelion.
Da'ath's name origin is trace from the Kabbalah, a religious diagram consist of the Ten Virtues (Sephirot), known as the Tree of Life. It is meant that all ten sephirots united as one and exist as a perfect state of infinite sharing.
Since the anime ended, Da'ath's whereabouts remains unknown.
