Kimi no Meniutsuru Iro wa: Aru Hi Totsuzen Do-S Ouji no Tsuma ni Narimashita

Count Fretzen's daughter Natalia, who was born with the unique ability to see the colors of people's emotions, tends to stay at home because of her unique constitution. When she goes to crowded places, she becomes intoxicated by the swirling colors of the crowd's emotions. Realizing that things couldn't continue like this, her brother brings her to a grand ball held by the Duchesse de Bussel, a powerful aristocrat. There, she meets a man wearing a horrifyingly ugly, dreadful color. To her surprise, it's His Royal Highness Prince Ludwig, the second prince of the Kingdom of Almgard. He approaches Natalia…?

(Source: Luna Bunko, translated)