Ryuuou Heika no Gekirin-sama: Honzuki Nezumi Hime desu ga, Nazeka Ryuuou no Saiai ni Narimashita

In a fantasy world inspired by ancient China, thirteen clans rule the land, and the Rat Clan is the weakest. Rueiin, the princess of the Rat Clan, is summoned to the land of the dominating Dragon Clan along with the princesses of the other tribes. The Dragon King seeks a bride, and they are all candidates! Instead of vying for the Dragon King's favor, though, Rueiin takes the chance to lose herself in the palace's enormous library—a place she can read to her heart's content, since she's driven by an insatiable curiosity. It's there that she's "found" by the Dragon King himself, who immediately kisses her and claims she's the one for him?! A fantastical love story begins!

(Source: Seven Seas Entertainment)