Brunhild the Dragonslayer, manga Vol. 01

Eden is a place of perfection, protected from outside harm by the silver dragon. In this idyllic land, the dragon raises a human girl found on the island's shores as his own. But when the dragon's life is mercilessly snuffed out by human machinations, the girl must choose whether to heed his dying wish and stay the course of righteousness…or walk a path of vengeance.