Kekkaishi

Yoshimori Sumimura, a 14-year-old junior high school boy, is a Kekkaishi, an exterminator of monsters. He is vying with Tokine Yumikura to be the heir to the Sumimura clan. Tokine is older than he, and she is his childhood friend as well as his rival Kekkaishi. To save people from danger, and to make himself stronger, Yoshimori fights against monsters.