The Ayakashi Hunter's Tainted Bride 8

But that changes one night when she is attacked by a vengeful yokai spirit—an ayakashi—leaving her scarred with the mark of a demonic curse. Her cousin Akemi seizes the chance to steal away her fiance, but it doesn't matter. Reito now finds her repulsive, and Nanao is forced to wear a monkey mask to hide her scar and live the life of an outcast. Years later, she meets Yako, the willfull young scion of another noble family. When Nanao's mask shatters after an accident, Yako sees her face and is drawn to her beauty and great spiritual power. But there's more to the handsome young lord then meets the eye, and when Yako offers Nanao a way out of her torturous life, the new life that awaits her is filled with more mystery and intrigue that she could ever imagine...

Volume 8 of The Ayakashi Hunter's Tainted Bride manga series by Mamenosuke Fujimaru.