Long ago, two races ruled over the Heavens. Spirits, and angels. One day, a war broke out, and the angels banished the spirits to Earth, where humans had gone extinct and sealed them down there with a magic barrier. One day, an angel fell down to Earth and went on a journey to get back, but the spirits want to take their angels wings because they need seven angel wings to break the barrier and return to the Heavens. The angel needs wings, and a spirit's essence to return home, which is obtained by killing a spirit.