Omamori Himari

Yuto Amakawa is a very ordinary high school student. His parents divorced seven years ago, leaving him to live alone. He is often cared for by his childhood friend, Rinko, and is otherwise an extremely plain boy. Yuto has a severe allergy to cats, so when he refuses to get out of bed, Rinko uses her pet cat as her ultimate weapon to force him awake. On the morning of his sixteenth birthday, a mysterious beautiful girl named Himari suddenly appears. It turns out that Yuto is the descendant of the Amakawa family, one of the twelve Oni Slayer Houses dedicated to protecting humanity. Upon turning sixteen, he becomes the current head of the house, and Himari, who serves the Amakawa family, begins to "protect" Yuto based on a promise made with his grandfather. As Yuto and Himari continue to accept exorcism commissions, various beautiful girls who are incarnations of monsters begin to appear one after another. With the involvement of his childhood friend, Kurisaki Rinko, a romantic battle erupts.