Monster to Parent

Saika Kannagi is a run-of-the-mill high school girl whose world is turned upside down after her mother passes away. As if the shock of being adopted by her mother's distant relative and having three handsome new stepbrothers wasn't enough, she's tasked with the divine duty of god-rearing—raising an infant god until it's strong enough to return home and take on its role as an all-powerful being! With the stress of a new family, a new school, and some unexpected twists along the way, this task won't be as easy as it sounds.

(Source: J-Novel Club)