Ayame-Senpai Wa Boku To Himitsu No Keiyaku WoAyame-senpai wa Boku to Himitsu no Keiyaku wo; Ayame Senpai to Boku ha Himitsu no Keiyaku wo; Ayame-senpai Made a Secret Contract with Me.; あやめ先輩は僕とヒミツの契約を; 绫目学姐与我订下的秘密契约; Líng mù xué jiě yǔ wǒ dìng xià de mìmì qìyuē

On his way home from school, Mitsuya Daikiーan ordinary high school student finds a girl covered in wounds. Upon closer look, he finds that the girl has animal ears, but she licks Daiki's ears and leaves. Daiki begins to wonder if it was just a dream, when Sakuragami Ayame appears upon him…? After telling her of the ability of Daiki's ears, Ayame feels responsible for dragging him into this, and proposes an oath of absolute servitude to protect him at all costs! - (http://www.takeshobo.co.jp/book_d/shohin/2820601)