Magu-chan: God of Destruction, Volume 1: The Girl Ruru Miyanagi (Magu-chan: God of Destruction #1-7)

Ruru Miyanagi is an ordinary girl who lives in an ordinary, somewhat boring, rural seaside town. One day, while digging for clams, she finds a beautiful gemstone buried in the sand. Her hopes of cashing in the gemstone are thwarted when she notices a tiny crack in it. But when she tries to fix the crack herself, the gemstone breaks, and Mag Menuek, the God of Destruction, appears in its place. Thus begins Ruru’s new life of living with an immortal, somewhat-adorable God of Chaos hell-bent on taking over the world!