Mahoutsukai no Yoru, english title Witch on the Holy Night, is a linear visual novel released April 12, 2012. The story was originally drafted in 1996, and would become the basis for the shared world of Nasu's later stories and games, though it was never published. Mahoyo is a rewritten version of that draft.

The story revolves around three high schoolers and their intertwined lives. Aoko Aozaki, the primary focus character, is the heir to her family's legacy and magic, by day she lives the life of a normal schoolgirl and by night she's tutored in magecraft by her roommate. Alice Kuonji is Aoko's roommate and the daughter of a witch and a wealthy businessman, born into a life of luxury and solitude, who owns the mansion she and Aoko live in. Soujuurou Shizuki is a fish-out-of-water from a rural mountain village who moved to the city to attend high school and stumbles his way into the two girl's lives.

Mahoyo is structured more like a slice-of-life than an action story. Everyday interactions and developments between the characters make up the bulk of the story, which moments of fighting and action dispersed between as the two girls try to keep their lives as mages safe and secret.