Mei is a supporting character in the narrative who serves as the maintenance foreman for the First Troop of Para-mails at the Arzenal base. She is a member of the "armorsmith clan," a lineage of technicians responsible for maintaining the powerful and unique Para-mail known as the Villkiss. Following the death of her older sister, Zhao Fei-Ling, Mei inherits this crucial duty, becoming the primary individual in charge of the Villkiss's upkeep, repairs, and upgrades. Her technical expertise is depicted as vital to the efforts of the Libertas organization, as the Villkiss is a central asset in their battles.

In terms of personality, Mei is characterized by a strong sense of duty and determination. She is deeply committed to her work and is willing to put her life on the line to ensure the Villkiss remains operational. Her dedication goes beyond mere mechanics; she claims to be able to understand the feelings of a Para-mail's pilot through her maintenance work, suggesting a high degree of empathy and intuition regarding the pilots she supports. Despite being one of the youngest members of the Arzenal staff, she is also recognized as one of the most knowledgeable mechanics on the base, commanding respect for her skills and professionalism.

Motivation for Mei is closely tied to her inherited responsibility. She takes her role as the Villkiss's guardian seriously, understanding that its functionality is a top priority for the survival and success of her comrades. She is also among those aware of the larger plan known as "The Libertus," indicating that she is trusted with sensitive information and is committed to the broader cause of the Norma, not just her immediate duties.

Within the story's progression, Mei plays a key supportive role. When the protagonist Ange disappears with the Villkiss, Mei takes the initiative to form a recovery group with other characters such as Salia, Vivian, and Ersha to search for her. During critical battles, such as when the Arzenal base comes under attack, Mei is shown taking command of her maintenance crew, giving clear orders to prioritize the Villkiss and manually moving it to safety under fire. Her actions during these high-stakes situations demonstrate her bravery and leadership. Following the fall of Arzenal, she is seen aboard the ship Aurora alongside other survivors, continuing her role as a crucial member of the crew.

Key relationships for Mei include her connection to her deceased sister, Fei-Ling, whose death is a significant event that shapes Mei's path. She works closely with the protagonist Ange, ensuring her machine is battle-ready. She also has a professional relationship with other members of the First Troop and the command structure at Arzenal, including Jill. Her interactions with the pilots, particularly through her empathetic approach to maintenance, create a bond of trust and understanding between her and those who risk their lives in combat.

Mei does not exhibit any notable paranormal or combat abilities. Instead, her value lies entirely in her exceptional technical prowess. As the youngest and most knowledgeable mechanic at Arzenal, her skill set is essential for maintaining and troubleshooting the highly advanced and often damaged Para-mails, ensuring that the fighters can continue their missions.