An office worker named Konoha Satou dies in a traffic accident and reincarnates as Iana Magnolia, the villainess from a self-insert fantasy novel she wrote during her embarrassing middle school years. In her original story, Iana is the evil younger sister of the perfect heroine Konoha Magnolia, and she is destined to be executed after trying to murder her sister. Armed with complete knowledge of the plot, Iana uses her understanding of every death flag she wrote to avoid her grim fate, protect the heroine she loves, and survive in a world filled with the cringeworthy characters and scenarios of her own creation. Her actions begin changing the story's events and the hearts of those around her, including Sol, the cold butler originally sent to assassinate her, and Yomi, a villainous childhood friend she wrote to be obsessed with her.

The OVA, bundled with the 18th volume of the manga, presents two new stories that expand on the main narrative. The first story, Yomi, Jealousy, and a Birthday, focuses on the complex and possessive feelings of Yomi, exploring his jealousy and his relationship with Iana during a birthday celebration. The second story, Iana and Sol's Feverish Day, is a lighter, more character-driven episode depicting a day when Iana and Sol are both bedridden with a fever, leading to moments of vulnerability and intimacy between the former villainess and her devoted butler. Produced by Studio Deen, the OVA maintains the series' signature blend of comedy, romance, and isekai fantasy, allowing fans to spend more time with its self-aware heroine and the cast of characters she originally created as fictional archetypes but has come to know as real people.