Kekkaishi e no Tensei

Barrier Masters: wielders of a rare and powerful guardian magic, entrusted with the lives of those under their protection. When his life on Earth ends, Lynos is fortunate to be reborn and to inherit this special gift. What’s less fortunate is that he’s been reborn as a child, and slated for sale as a slave. Narrowly avoiding a dire fate, he is taken as a servant by a prosperous noble family, where he is trained to become the guardian of its reigning members. Step by step, one trial after another, Lynos prepares for a life of adventure as a Barrier Master!

(Source: Seven Seas Entertainment)