The Spirit is a bullet developed by the Elder Hamilton for the purpose of creating a bullet more powerful than the Gospel, using a repressed lower-class Demon for its explosive power, but upon test-fire it was found to be too dangerous, because with one shot of the Spirit the Demon inside it became free to attack anyone in sight including the shooter, making Spirit a failed experiment. After this the Elder changed his plans from making a more powerful bullet to a more powerful Gun, the result of this change being Tetragrammaton.