I Just Want To Retire Peacefully, But My Apprentice Is A Regressor

Nathan never considered himself a good person; he just had his bottom line. Therefore, when he did not have much time left to live and met his benefactor's son in a difficult situation, he could not bear to leave the child alone. He raised the child as if the child was his own. He hoped that before his imminent death, the child would be able to survive by himself. However, What went wrong? Why was everything different from what he thought at the beginning? ... Theodore's life was never easy. He was just an abandoned child. He spent his life attempting to go further on the path of mana user. He did not regret dying without reaching the peak. When he closed his eye to accept his death, his last thought drifted to his childhood with that person who cared for him. When he opened his eyes again, he really did return to when he was a child. ... This story is about a mysterious retiring teacher and his not-so-simple apprentice. ... Update: Every Sat and Sun Note: Extra chapters depend on the situation I will try my best with the update; Thank you very much.