Koushaku Reijou no Rouraku Mission: Maou to no Seiryaku Kekkon ga, Jinrui Saigo no Kirifuda desu!... tte, Maou ga Onnanoko no Baai wa Dou Sureba Ii no desu ka!?

Cecilia, the duke's daughter, has been given a critical mission to maintain peace between humanity and the Demon King. To do this, she must win over the Demon King's heart and avert her people's destruction. But when she arrives to meet her betrothed, the Demon King isn't at all what she anticipated! Rather than a terrifying beast, Cecilia is engaged to a beautiful and innocent-looking young woman!