Crimson Wind (2005)

The year is 520 of the Landa calendar, and Sei is a new cadet in the military. Coming from a family of soldiers, Sei easily wins the annual fighting tournament. However, unknown to Sei, the trophy wasn’t the only prize he won that day. Looking on from the aristocrats' balcony, Touri was captivated by the handsome young swordsman--and vowed that Sei would become his.

Source: www.anisearch.com/manga/4783