It's Not Your Baby!

Histoire

Callia Taxicate was a mere commoner until she saved the life of Simon Tereloane, the son of a duke. In return, the duke helps make her commander of the emperor's knights and she becomes a war hero. Though she only sees Simon as a friend, the two unexpectedly spend the night together and she ends up pregnant! Terrified that he and his noble family won't accept a child out of wedlock, Callia runs away to raise the baby on her own. But how long can she hide this secret, especially from the father?!

Synopsis via AniList (en anglais).