Nina has never known romantic love. After a friend recommends the otome game Sword and Magic Adolescence, she plays through it but only achieves the friendship ending. Determined to experience love, she starts a second playthrough only to be suddenly transported into the game world as its heroine, the saintess Nina. She embarks on adventures with her companions, saves the world, and again reaches a friendship ending. On the night of her victory, however, she is stabbed by an unknown assailant and forcibly returned to the real world.

Two years later, Nina discovers that a sequel to the game has been released. Driven by a desire to see her friends again, she wishes herself back into the game and is reincarnated in the sequel's world — this time as a nameless village girl, a mob character with no role in the story. Despite her lowly status, she discovers that all her attributes from her previous life, including her magical abilities and the affection levels of every character, have carried over at maximum value. There is one alarming exception: the affection gauge of Prince Alvin, her former capture target, has turned completely black.

Nina resolves to live a quiet, peaceful life in the countryside, using a transformation spell to hide her identity and her overwhelming power. Yet her plan quickly unravels when the new heroine of the sequel, a girl named Erica, sees through her disguise with her own saintly abilities. Alvin and the other former companions soon recognize Nina as well, and Alvin confronts her with an intense, possessive confession that she is completely unprepared to handle. Meanwhile, the mysterious figure who murdered her in the first world reappears in the sequel, forcing Nina to confront the threat that ended her previous life.

As the story progresses, Nina must navigate the overwhelming affection of her old friends, the emergence of a genuine romantic awareness she has never felt before, and a growing danger that threatens everyone she cares about. The narrative blends her struggle to maintain a humble existence with the escalating attentions of a yandere prince and the investigation into the bug-like anomaly that killed her, all leading toward a confrontation that will determine the fate of both worlds.