Ryuujin-sama to Kurashitara

On the way to school one day, Nao stumbles upon an unconscious kid by the river, only to find out that the young boy is a dragon god endowed with mystical powers! Nao agrees to help the kid, who is in search of his lost mother. And thus begins the unlikely story of how a clumsy high school boy ended up living with a cute, tiny dragon god.

(Source: MangaPlaza)