Gakeppuchi Reijou wa Kishi-sama no Kyuuai ni Kidzukanai

Lucia, a poor noblewoman raised to be the next lord, excels in sword and archery and has studied estate management. But her younger brother, born four years later, inherits the title. Determined to contribute to her family’s future, she chooses marriage as a means to support her domain. At a garden party, she heroically intervenes in an attack—but unwittingly draws the attention of Reinellio, the famously charming captain of the duke’s knight guard. He proposes a fake-relationship arrangement, and her supposed act of convenience turns into something more meaningful as she begins to understand the real man behind the rumors.