For generations, the Kagurazaka family have possessed the power to speak with the messengers of Inari, a power that has been sustained through the centuries by intermarriage with women of the Ujou family. Having waited long for his bride, Rio, the current heir to this power, is shocked to find himself abandoned by his bride-to-be when she elopes with another man. Shortly after, her younger brother Nagi presents himself to the shrine as her replacement, declaring "As a man, I can't produce offspring, but I can have sex."

(Source: Hero Scans)