Uchi no Ko no Tame naraba, Ore wa Moshikashitara Maou mo Taoseru kamo Shirenai.

He met a girl. A young girl branded with the mark of a criminal. That was the beginning of everything. "Crap, my girl's so cute"

This is the story of the two who became an overly protective guardian and an adopted child, changing relationships, and furthermore until how that relationship evolves.