Cast Away as a Sacrifice, Loved as a Saint by a Frontier Marquis

"I've had enough of being oppressed! When she sells herself to the family of a border count, she is called a saint...!" Tsundere x love love x reversal of fortune! Luana, the bastard daughter of a family of mages, was treated coldly by her family. One day, she is sold to the family of a frontier count on the front line of battle against demonic beasts... But she still doesn't want to die on someone else's orders. In fact, Luana has a secret she hasn't told anyone... I don't know if this will help, but it is the only weapon I have! Since the day she first stood on the battlefield with Sieg, the son of a border count's family, she has been called a "saint"! A realistic romantic comedy with a tsundere son!