Humankind was on the brink of extinction after Demon Lord decided to invade human world and bring destruction upon it. Humankind believed that one day they would end the disasters that fall upon them and their world would see peace once more. Against of all odds, a group of skilled magicians finally slay Demon Lord Zarth and beat his army. Just when they certain they survived the battle, they faced an explosion magic that killed them. Ren Milford, one of the survivors believe that he died from the explosion, but went back to his early days when he studied at prestigious magic academy. With this second chance, Ren determined to save not only himself, but also the friends and comrades he once lost. With the knowledge of the future, can Ren makes a difference and prevent the fall of humanity or humankind will face the same terrible destiny again?