Swallows by Natsuo Kirino

Twenty-nine-year-old Riki is sick of her dead-end job, of struggling to get by ever since she moved to Tokyo from the country. So when someone offers her the chance to become a surrogate in return for a life-changing amount of money, it's hard to turn down. But how much of herself will she be forced to give away? Retired ballet star Motoi and his wife, Yuko, have spent years trying to conceive. As Yuko begins to make peace with her childlessness, Motoi grows increasingly desperate for a child to whom he can pass on his elite genes. Their last resort is surrogacy; a business transaction, plain and simple. But as they try to exert ever more control over Riki, their contract with her starts to slip through their fingers.