Esme is a young female Coerlfolc.
She is Sam's younger sister, and is not knowingly peculiar.
The children met Esme when they take shelter in her house during a bombing. Esme is told by Sam to hide in the bathtub when Germans attack, as it is speculated that a bathtub protects one from a bomb. She offers to share her bathtub with the peculiars, which they refuse. Later, Enoch calms Esme down by letting her play with his homunculus. Unfortunately, this use of this peculiar power attracts hollowgast. When the peculiars try to convince Sam to come with them, Sam states she cannot leave her sister, who is not peculiar and cannot enter loops.
She is the only one who seems to enjoy being around Enoch, because she liked the clay 'soldier men' he made for her to play with. Her age is around six, and similarly like her sister, she most likely did not survive the war.