Ayakashi Oniyome Konintan

Having grown up completely alone in the world, Riho was adopted into the Hanabishi family and endured harsh days of being mistreated by everyone around her. Then, on her 17th birthday, Riho's adoptive father tells her she must become a "sacrifice" to a yokai. But the Emperor of the yokai appears before the despairing Riho, and it seems he intends to welcome her not as a "sacrifice," but as a "bride"—!? (Source: AlphaPolis, translated)