"Hey, I want to fall from grace."

  It all started with those words.  

  Lilith and Guest have been together since childhood. Lilith, who loved mischief, would often play pranks with Guest and run away from the angry angels. Those casual moments with Guest were what Lilith loved more than anything else.  

However, it seems God will not allow such times to last forever. One day, Lilith, a high-ranking angel, is told by a Dominion that a divine oracle has been received: "When thou reachest the end of thy 900th year, thou shalt be appointed as a Dominion." But becoming a Dominion means losing the status that allows him to be with Guest, and even his emotions will be erased. To lose emotions means losing all feelings for Guest and becoming an existence no different from a machine.

Naturally, Lilith does not want this. Refusing to allow it, he rebels against God. He kills humans, burns villages, and destroys church bells. He repeatedly commits sins that would lead to execution if discovered by God.

However, because Lilith holds a position high enough to be appointed a Dominion, he is under strong divine protection, making it difficult for him to fall. His goal is to commit a sin great enough to cause a fall from grace before God notices and executes him.

Everything is for the sake of falling and being with Guest forever.