Ernesta

Ernesta is one of Charlotte's retainers and acts as her guard knight.

Spoiler from Part 4 Volume 4

While Ernesta was born and raised in Haldenzel, she has been living in the capital ever since becoming Charlotte's guard knight. Thus she is unfamiliar with the changes that happened to establish a printing industry in the province until she accompanies her mistress at a trip there when Charlotte goes with Rozemyne to check on the printing industry and deliver the small chalices for Spring Prayer.