Overview
Frieren's signature expression whenever she feels sleepy, freezing, confused, upset, or trying to hide something.
Related Illustrations
Digression
Serie also showed this expression when giving the magic book to Fern after she was promoted to First Class Mage in chapter 60 of the manga. According to Fern, at that time Serie gave an incredibly dissatisfied look with that request (this is because Fern only asked for a mediocre magical reward, disproportionate to her magical potential).