Migawari Konyakusha nanoni, Ginrou Heika ga Doushitemo Hanashite Kuremasen!

When her sister, the king's fiancée, disappears, Countess Iris is forced to go to the royal palace to take her place. The king is rumored to be a tyrant, cursed with the blood of the silver wolf, that will surely lead to the ruin of his house! She tries to avoid it, but she ends up spending the night with him! Iris thinks she is doomed, but then she finds out that the king, who is supposed to be a vicious beast, turns out to be more like a cuddly puppy, and she can't help but fall for him!

(Source: Kadokawa, translated)