The protagonist is reincarnated as Ruibel Azestar (also known as Ruru), the third princess and a minor character in the fantasy novel Chronicles of the Hero of Light.

Though she was supposed to be just a background character, Ruibel is suddenly proposed to by the novel’s protagonist, Heizen Icehan. Overjoyed, she begins to believe, “Maybe I changed the original story!” and lives happily in that thought. But one day, Ruibel witnesses Heizen cheating on her. That’s when she realizes this world isn’t based on the novel—it’s based on a notorious, infamously awful dating sim inspired by the novel. And she’s just one of the disposable “romance targets” for Heizen. Furious and burning with a desire for revenge, Ruibel finds herself approached by none other than Ancelot Ruenhart, the prince of a neighboring country, infamous as a "bloodthirsty madman."

“You want revenge on him, don’t you? Use me, Princess.”

For some reason, even though they’ve never spoken before, Ancelot takes an interest in Ruibel… A near-doomed romance fantasy between background-character Princess Ruibel Azestar and the mad prince Ancelot Ruenhart!