From Chibi Manga:

Ria Kageyama prays to God every single day. She feels like it's her fault that her parents and her favorite nun all passed away due to her unfortunate nature, so she's determined to stay away from other people and devote herself to prayer. Until she starts high school and runs into the fierce delinquent Renji and the handsome heartbreaker Kinzou, who both fall in love with her and promise to take care of and protect her!

(Source: Shogakukan, translated)