In the 305th year of the Alcian calendar, humanity is under the dominion of 'numbers,' where each individual is marked with a unique 'Count' at birth. This Count could signify various things, like the distance traveled on foot or the praises received for one's culinary skills. Falling to a Count of zero results in banishment to the dreaded Abyss. When Hina's mother's Count reaches zero, her dying wish is for Hina to seek out the enigmatic figure known as the Legendary Red Baron.