A brief description of the Shikkaku Mon No Saikyou Kenja manga:
In the world there is a Sage – a man who has won good fame through achievements in magical battles. He decides to comprehend all possible martial arts in order to become stronger. Years of training and exercise have led the Sage to the conclusion that his body is unable to bear the magical battles. But he did not give up and captured his soul by magic in order to rise up in many years. And so, at the coming of the centuries, the Sage revives and sees a completely unfamiliar world in which the level of magic is incredibly low. But what will he do now?