The Do-Over Damsel Conquers the Dragon Emperor, Vol. 5 (manga) — Sarasa Nagase

I'm sure His Majesty will have these worries during that critical time in the future...As Jill continues training with the Dragon Knights, she runs into Lawrence Marton, one of Prince Gerald's servants who was her aide-de-camp in the original timeline. But Lawrence is firstly a shrewd spy, and with their companionship having never happened, can she really trust him this time around? What's more, Jill determines that Hadis's older siblings, Princess Elentzia and Prince Risteard, could be valuable allies in protecting Hadis. She'll have to persuade them to join her side -- before the imperial army's next attempt to draw out the Dragon Emperor ends in disaster!