Kekkaishi

This is [Kekkaishi] by author Tanabe Yellow. It was serialized in Weekly Shonen Sunday from 2003 to 2011 and concluded with a total of 35 volumes. The story revolves around clans that use a unique form of sorcery to create rectangular spaces, trapping and destroying yokai. There is a mystical land called Karasumori that attracts yokai, and the story features the successors of two kekkai families, Sumimura Yoshimori and Yukimura Tokine, who have carried on the family business for 400 years to protect this land. There are also various other ability users and yokai involved, making it interesting to watch. Although the power level drops a bit towards the end, it's still not bad.