OPEN-ENDED LOVE INTEREST: Y/n was taken in by Ritsuka Tachibana's grandfather as a baby, growing up beside Ritsuka and Lindo. The plot begins unraveling around them as Ritsuka's 17th birthday nears, and the hunt for the "Forbidden Grimore" leads to the traumatic experience of witnessing Ritsuka's mother's kidnapping. But what secrets lie behind Y/n's presence in the Tachibana's house?