Konyaku haki sareta henkyou haku reijou desu ga, teki kokuou ni kyuuai sarete hanayome ni narimashita

[A popular work from Shueisha's Chiffon Bunko imprint is finally getting a manga adaptation!] "Surely this encounter is poisonous..." Emma, the daughter of a frontier noble family, is an eccentric who enjoys researching poisons as a hobby. Heartbroken after her fiancé, Crown Prince Charles, suddenly breaks off their engagement, she returns home, only to receive a sudden marriage proposal from King Alphonse of a neighboring country!? Threatened with war if she refuses, Emma reluctantly marries Alphonse, but she becomes intrigued by him, as he is unaffected by poison, and in order to uncover his secret, they begin to share their bodies... https://www.cmoa.jp/title/324381/