Kekkaishi e no Tensei

A 34-year-old man working at a demanding company wakes up in a strange world, reborn as a six-year-old boy. Unaware of his latent "Barrier Master" ability, he ends up at a slave market and is put up for auction. When no one shows interest in buying him, he is marked for disposal but is saved at the last moment by Marquess Basam. The marquess takes him in and raises him as a personal Barrier Master under the name Linus. As he begins to develop his abilities, he continues to face various challenges and struggles to survive.