Sokutaijou Shitai Wakiyaku nanoni, Netotteshimatta Oujisama ga Nigashite Kuremasen

"Do you think you can just sleep with me and get away with it by claiming it was a mistake?" Estelle, the daughter of a viscount, was reincarnated as a supporting character in a certain popular web novel. Estelle's role in the novel is to be condemned and exiled by the heroine for sleeping with her lover, the second prince. Wanting to leave the story quickly, Estelle plans to "pretend" to sleep with the second prince as the novel goes along... but she accidentally calls out to the hero, first prince Oscar...?! (Source: Ichijinsha, translated)