I met a duke's son who starts with denial, and I am twisted from being loved only for my younger sister.

Viscount's daughter Brune was not expected by her parents since childhood and was looked down upon by her younger sister Fione. Even when she entered society, all the men who approached Brune were only interested in Fione. Then one day, Brune meets Duke's son Livel, and he suddenly proposes to her. However, Brune, who sees herself as worthless, says―― "I'm not cute, am I?" "No, you're cute." "You won't be happy if you marry me, will you?" "No, there's no greater happiness than this." Livel continues to deny every question Brune poses to him...