Letizia

Letizia is biologically the granddaughter of Aub Ahrensbach and current successor of the title of Aub Ahrensbach.

Spoiler for Part 4 Volume 5 According to Rozemyne, she is "a very cute girl with blonde hair and blue eyes".

Letizia was born in Drewanchel. When her uncle Wolfram died, Aub Ahrensbach negotiated with Drewanchel and managed to adopt Letizia back into his duchy to make her his successor.