Mita Aoi Book order (chronological)

First published in Japan in 2017 by KADOKAWA CORPORATION, Tokyo.

Though self-conscious at first about his small horns, Eru has been able to open up his heart to his roommate, Rihito. But now, Eru has caught the attention of Rihito's genius and dangerous cousin, Haruto - who's trying to make Eru his servant?!