Ojousama Wa Oyomesama

From StarryHeaven:

Towako the ojousama (daughter of a high class family) will be turning 18 years old soon. When she was very young, she was told that on this 18th birthday she is to marry the young man who was born on the same day, the same time, and the same year as she was. However, during their first meeting, Yuuga was incredibly mean to her! What's Towako to do when her husband-to-be is the shy and cool type of guy?