Billion, a city that is ruled by a sinister man named Harry MacDowell and his organization, Millennion, has become the only safe place for a fugitive girl named Mika Asagi, who falls under the protection of an undead man called "Beyond The Grave". Grave, returning from the dead with no memory, wanders in search of his past, and after defeating some of Millennion's best soldiers, Harry's executive branch issues a manhunt on Grave, with Harry suffering from untold resentment for Grave.