How I Became the Bodyguard of the Saintess!

The story takes place in a world full of magic, with knights and wizards, but also monsters and demons. Our protagonist is an ordinary boy, with one particularity: he grew up alongside one of the most powerful girls in the world, the Saintess, the great protector of the light. This is the story of an ordinary boy, and a very extraordinary girl who happens to be his childhood friend. How, because of an unfortunate accident, he has to become her bodyguard. How they will have to fight together against terrifying darkness.