Hera is a descendant of the Shield Maidens and is all that remains of the brave warriors that fended Rohan when all the soldiers fighting were wiped out. One day, the Lord of West March, Freca decides to demand Hera's marriage for his son instead of betrothing her to the enemy. When King Helm disagrees, a duel occurs and the King of Gondor...

One day, Naho Takamiya receives letters that claim to be from herself ten years in the future, each letter describing a different day and what she must do to prevent her "biggest regret". At first, she thought it might just have been a prank but just as the letter described, Naho and her friends befriend the new transfer student named...