November, the start of winter. Kirihara Academy for Girls, a missionary boarding school located in the remote Japanese mountains. It's here we find our protagonist, Shiratori Ritsu, the sole male allowed on campus and the school priest. Never once has he set foot outside the academy grounds, which protect him from demons lusting after him. But the girls of this academy come to him, believing he's their guardian angel, and he obliges. For he is burdened by the death of a girl, which strengthened his resolve to make others happy. This constant mix of the holy and the sinful has him just barely holding onto his sanity. And the sudden arrival of a new girl raises the curtain on a whole new story. For she is the one-hundred-year-old vampire, Mary Harker. However, her infiltration of the academy brings with it another surprise... Namely, a phone call from the devil. Can these powers of his truly bring joy to people's hearts? For what reason was he born? This is a tale of life, woven into prayer.