She's traveling to the capitol in place of Leon Muno, her father, who's busy supervising the reconstruction of Muno barony after the demon attack. The LN goes into a bit more detail. The noble families are require to report in person to the King. Leon and his adviser, Nina, have been exchanging letters with the King about the incident, but needs to send adult family in his stead to do an official audience. (Also of importance is the fact that Leon has been officially recognized by the city core that was cursed by Zen.)
I think Orion-kun is supposed to be 13? So he's just a bit young to do the trip on his own recognizance.