Junjou Oni to no Dekiai Kon - Urareta Saki de Shiawase ni narimasu

Harada Matsuri (20), an office worker, lives with her mother. One day, she is told by her mother, "I have decided whom you will marry." To her surprise, a stranger gave her some money in exchange for her marriage to Matsuri, and she had spent the money as well. She is forced by her mother to quit her job and kicked out of her house, and she is terrified of what she will be forced to do to the man she is marrying. Matsuri is surprised when the beautiful, expressionless man tells her she doesn't have to do anything. When Matsuri insists that she cannot do such a thing in order to repay the money, Oniichi whispers to her that he wants to eat her. Matsuri's mouth is covered with sharp fangs...?