If It's Not Us

A week before the wedding, the bride-to-be 'Ina' becomes possessed by 'Eve Rectory', the main character in a novel whose title she does not know, the day after a quarrel with her boyfriend about marriage. It's scary to be possessed by a character I don't know, but they are from a horror novel that was discontinued without being completed?! What's more, the subject is necromancy... !

Can Ina return to reality in the suspicious-looking Rectory House?

(Source: Naver, translated)