I recommend the novel "One-Punch Nanny Dad." The male protagonist was very powerful from the beginning and was called "Fist Saint." He lived a low-key life in the Otherworld and took on the position of an elementary school teacher. In this foreign world, he successfully led a group of students to survive in dangerous environments and gained considerable fame. In addition, he saved an angel and became her guardian. I hope you like my recommendation. Muah ~