Wolf Girl and Black Prince

Erika talks to her friends about boyfriends and romance, but in all her sixteen years she's never actually dated anyone. She thought her lies had reached a limit until one day she takes a surreptitious video of a good looking guy she saw in town. She brags that he's her boyfriend, but it turns out that his name's Kyōya Sata and he's just transferred to her school. She tells him what's going on and offers to admit to her lie, but it turns out that under his sweet exterior, he's actually a malicious sadist. Seizing on Erika's weakness, he orders her to be his dog.

Synopsis from Anime News Network