Kettou Shijou Shugi Meika no Youshi no Yarinaoshi

In a world ruled by bloodline, magic belongs to the nobility, until a demonic invasion makes their power useless and drives humanity toward destruction. Colin, a slave-born swordsman and humanity’s last hope, discovers the Forbidden Book, which lets anyone learn magic, just before he dies. Colin awakens five years in the past as a boy. Determined to change the future and save humanity from the demons, he sets out to rule the world as a Magic Swordsman, wielding both sword and magic.