Office worker Satou Konoha dies in an accident and is reborn as a character from a story she wrote as a student—The Dark History. Instead of reincarnating as the heroine as she'd hoped, she's the hated little sister, Iana. And, according to the story, she's destined to perish early on at the hands of her butler! There's only one way to survive—remember the plot of the story and avoid her fate!

To save Konoha from the monster that kidnaps her, Iana triggers her own death flag. With help from Sol, Ginoford, and the others, Konoha's rescue succeeds. Iana barely has time to relax before an invitation to a ball arrives from the capital—the very ball that's the setting for chapter 3 of The Dark History. If Konoha dances with the prince at the ball, it will lead to a death flag for Iana!

As Iana grows used to life in the world she's been reincarnated into, a young man comes to visit—her childhood friend Yomi, back from studying abroad. When Iana remembers Yomi, a character she created, she is left aghast.

Yomi mistakenly believes that Sol is oppressing Iana. Out of pure feelings and loyalty for Iana, he tries to kill Sol. Konoha is attacked by a man-eating flower created by Yomi's magic. After defeating it with Ginoford, Sol begins to suspect that suspicious events happening around him are also targeting him, and turns his eyes to Iana. Yomi declares, "I did it," and challenges Sol to a duel!

Iana confronts Yomi, taking up Sol's sword in his place, but it's so heavy that Iana can't even swing it. Yomi, who loves Iana, concedes the duel, casting his own sword aside. The matter is settled for the moment, but if nothing changes Yomi will keep trying to kill Konoha. No amount of persuasion from Iana seems likely to make Yomi give up. What desperate measures has Iana come up with instead?

Iana sneaks into town with Konoha where she sees just how popular Konoha is, and how despised she is herself. Back at home, a man named Cheneau drops by. He's vice captain of the Police Security Force's Hydrangea Unit, and he once arrested Iana on suspicion of Konoha's attempted murder. He's been investigating the disappearances of beautiful young ladies, and he has his eye on Iana as a suspect.

Iana heatedly declares to her new friend Menoa's older half-sister, "This girl is no slave!" By causing an uproar at Duchess Amaryllis' party, Iana attracts even more suspicion from Cheneau. And right at that moment, Menoa disappears. Iana, who found and picked up the earring that Menoa was wearing, is suspected to be the culprit behind the disappearing beauties incidents.

Duchess Amaryllis is Bloody Rosa, the person who has been kidnapping beautiful girls. In order to save Menoa, Iana convinces Cheneau to help her, and they commence working together. But a trap sends Iana and Cheneau tumbling into Duchess Amaryllis' hands. The two are held captive in the basement—an insane "paradise" where the kidnapped Menoa and Cheneau's younger sister are also being held.