A brief description of the Kenja No Mago manga:
Magic has helped mankind many times to escape the catastrophes that could destroy the universe. Shin is a boy who remembers his past life. He was picked up by an old man nicknamed “The Sage”. He lived in the forest, hiding from civilization, raising Shin as his own grandson. Thanks to the fact that the boy remembers his past life, he quickly mastered the art of the sage and finds the opportunity to create his own magic.
Shin finally turns 15. At this time the Elder decides that it is time to let the boy go to the big world to live his life. However, he has forgotten that Shin does not possess common sense at all, as he has spent almost his entire life in solitude with the old man. The boy joins the Academy of Magic in order to join society and find use of his unique skills. But will Shin be able to integrate into society?