A werewolf, also known as a lycanthrope, is a mythological or folkloric human with the ability to shapeshift into a wolf or an anthropomorphic wolf-like creature, either purposely, by being bitten or scratched by another werewolf, or after being placed under a curse. The werewolf is a widespread concept in European folklore, existing in many variants which are related by a common development of a Christian interpretation of underlying Indo-European mythology which developed during the medieval period. From the early modern period, werewolf beliefs also spread to the New World with colonialism.
Belief in werewolves developed parallel to the belief in witches, in the course of the Late Middle Ages and the Early Modern period. The legend of the werewolf, however, is said to have existed for far longer. The earliest known account of a man shifting into a wolf is found in the Epic of Gilgamesh which is considered the oldest known prose from 2,100 BC.
The other recounts a Greek legend regarding a king known as Lycaon, who attempted to test Zeus' proclaimed divinity by serving him human flesh. Enraged by this, Zeus placed a cursed upon Lycaon, transforming him into a wolf, and killed his 50 sons with lighting bolts. However, Lycaon is said to have bitten his sons in order for them to survive the god's wrath and traverse the world to keep the lycanthrope lineage intact.
This transformation is often associated with the appearance of the full moon, as popularly noted by the medieval chronicler Gervase of Tilbury, and perhaps in earlier times among the ancient Greeks through the writings of Petronius.
"Origin: Tokyo. A demon and human fused into a beast. They have many ties to moon goddesses. Various moon goddesses take wolves' forms. The werewolves' relationship with the moon comes from these stories."
—Shin Megami Tensei A-Mode DDS dictionary
Giten Megami Tensei: Tokyo Mokushiroku
Werewolf appears as both Lycanthrope and Werewolf in the game.