Eva, known also as Effa, serves as matriarch to a lower city family in Ehrenfest. She is married to Gunther, a soldier, and mother to their three children: Tuuli, Myne, and Kamil. Before their marriage, Eva endured two miscarriages and the loss of their first son shortly after birth. As the daughter of Ehrenfest's former gate commander, she met Gunther during his apprenticeship under her father. Despite being a highly sought-after marriage prospect due to her beauty and household skills, Eva chose Gunther after his persistent courtship, surprising neighbors who saw him as goofy compared to her refinement.

In her mid to late twenties, Eva possesses jade-green hair and green eyes. Her commoner status is reflected in her practical attire: a tunic tied with a sash over an ankle-length skirt, her hair typically tied up and covered by a kerchief. By commoner standards valuing health, strength, and domestic ability, she is considered beautiful, with some noting her looks seem wasted on Gunther.

Eva works as a dyer at the Heuss Workshop and is an accomplished seamstress, though sewing isn't her primary trade. Her self-made garments, like Tuuli's baptism dress, draw neighborhood admiration. She exhibits a natural talent for needlework, quickly mastering crochet after briefly observing Myne. Her dyeing expertise later proves vital when she provides key insights on preventing color mixing during paper production, earning her professional respect for her textile skills and work ethic.

Sharing personality traits with her eldest daughter Tuuli—creativity with fabrics, kindness, consideration, and practicality—Eva generally maintains an even temper but occasionally shows exasperation towards the eccentricities of Myne and Gunther. She dislikes wastefulness and values frugality. Deeply protective of her family, Eva tirelessly cares for the often-ill Myne, including bedtime storytelling, and risks execution by defying a noble threatening her daughter. She also expresses admiration for the influential seamstress Corinna, becoming visibly flustered when Corinna evaluates her work.

Motherhood defines Eva's core. She supports Myne's unconventional pursuits despite misunderstandings, like accidentally using Myne's gathered wood for writing tablets as firewood. After Myne's adoption by nobles and departure, Eva copes by maintaining a neater home for Kamil. She later motivates Gunther through his depressive episode following Myne's leaving, using direct language to spur him back to action. Her relationship with Gunther remains strong, marked by mutual devotion and a healthy family life.

Eva's development includes expanding her family with Kamil's birth in Part 2 and adjusting to Myne's absence by focusing on household stability. Her protective nature evolves to encompass emotional resilience, supporting her husband and children through significant transitions while continuing her work as a dyer and seamstress.