Takaya Saiki

The main character in this series. A tough but surprisingly vain guy who cant be beaten by anyone at his school intellectually or physically and sets Lilim free by opening the pendant which was dropped on his head seemingly at random by a crow. He names her Lilim after her species since she has no name of her own. He makes a bargain with Lilim to be her sole provider of lifeforce so as to protect other men from her predations. Takaya convinces his parents to let Lilim stay at their house and eventually falls in love with her his personality mellowing greatly in the process. At the end only Takayas desire to be reunited with Lilim is capable of breaking the seal placed on her by Yukihiko. Wikipedia