Second part of Yoroi Shin Den Samurai Troopers.

Lady Carolina, the overlooked daughter of a powerful duke, has always believed herself to be the black sheep amid her illustrious kin. Her father is the distinguished prime minister; her elder sister, a prodigious mage destined to become their nation's next Saint. In comparison, Carolina resigns herself to a quiet existence in their shadows until a sudden and unexpected royal decree alters her destiny, thrusting her into a political marriage with the formidable Bloodthirsty Prince of the neighboring Empire of Malcosias. Determined to prove her worth, Carolina takes a bold step into a world fraught with both political and mortal peril. As royal obligations intertwine with hints of true love and the stirrings of her own latent power, Carolina moves ever closer to understanding what it truly means to be exceptional. (Source: J-Novel Club)

Elizabeth Leiston, the daughter of Haldoria's powerful prime minister, is the picture of a refined noble lady and the perfect future queen. But when her fiancé publicly humiliates her, calls off their engagement, and starts spreading nasty rumors about her, Elizabeth reaches her breaking point. Why should her only friend be her loyal maid, and why should she continue to serve a country that doesn't respect her? Elizabeth concludes she won't stand it any longer and will bring down the kingdom, even if it's the last thing she does! As such, she uses her quick wit and, more importantly, her seven magic grimoires to embark on a quest for revenge. And let her tell you, there will be hell to pay! (Source: J-Novel Club)