If You Win, Your Prize Is The Princess

Sylia, a swordsman, was a 15-year-old girl moving from place to place, making a living as a mercenary.
One day, she participates in a national competition to earn a lot of money and won it narrowly. However, the grand prize for that tournament was the princess of the royal family holding the event?!
The marriage goes through without Sylia knowing why. Thus begins a relationship with Luna, the 13-year-old princess and Sylia’s new wife. This is the story of how Luna feels Sylia’s pain, Sylia feels the warmth she’d never known in her life, and the two of them grow up together.