Shiratori Ritsu, the sole male at Kirihara Academy for Girls and its priest, protects the school from demons but finds his sanity tested by the arrival of a new student, the one-hundred-year-old vampire Mary Harker, and a call from the devil, questioning his purpose in life.
The story centers around Ritsu's interactions with the female students at Kirihara Academy, including the arrival of the vampire Mary Harker and the subsequent events. Players progress through the narrative by making choices during key moments, which can lead to different outcomes and character development, though these choices don't always significantly impact the overall plot.
Completing the common route allows players to access the individual character routes, with the order of these routes potentially affecting the player's understanding of the narrative and the connections between the various characters.
The game's visual presentation is a standout feature, with a diverse cast of characters boasting distinct designs and personalities, accompanied by detailed background art and a soundtrack that enhances the atmospheric tone. Full voice acting by a talented cast further contributes to the immersive gameplay experience.
The multiple character routes and the potential for varied choices and outcomes within each route provide substantial replay value, as players can explore the different relationships and narratives associated with each heroine, deepening their understanding of the game's themes and overall story.