18+ Heian Juukon Monogatari: Juujin Dannasama wa Shojo Hanayome wo Amaku Torokasu

This is the warm and tender tale of a lonely beast and a human girl... Shishi, who has the body of a lion and understands the language of beasts, is feared by the people of the capital because of his appearance. The one who has always had her heart set on him is Nene. Since a year ago, she has been a candidate to become his bride, but she spends her days worried he does not see her that way. One day, when her inflamed passions overflow and she tells him, "I want to be more connected with you," he pushes her down as if angry. A sweet and lewd Heian x pure love x beast marriage tale.

(Source: Bunkasha, translated)