Karisome Seijo wa Kyou mo Otaishi (Oshi) ni Kyuukon Sareru Watashi to no Kekkon wa [Kaishaku Chigai] Nano de Okotowarishimasu!

Ariasera, a saint candidate with exceptional divine power, receives a summons one day, only to find Crown Prince Siegfried there. "Would you be my fiancée?" "No way." He is none other than the man Ariasera fantasizes about in her "thin scriptures"!? She agrees, told it's a political engagement to save the country from crisis, but for some reason Siegfried's advances don't stop.. They promised not to get married, right!?