A doctor serving in the Demon Army. An elf and Maniol's older sister. Beyond healing magic and first aid, she easily handles high-level sorcery (Light, Earth, and Wind attributes). She appears to be popular and respected, but in reality, she is a free spirit who ignores social cues and uses whatever means necessary to get her way. Due to her personality, she has the power to be one of the Four Heavenly Kings, but she has absolutely no interest in the position. She is known for problematic behavior like turning the wounded into undead, interfering with army authority, or forcing people into physical exams for personal amusement. On the other hand, she does her job in her own way, such as treating delusional patients with placebos or acting as a listener for those in trouble. She seems to have a lot of free time in the Demon Army. However, she is a genius—her situational judgment is perfect, and she possesses the survival skills to overcome any crisis. She has known Maniol for a long time and looks out for her in her own way, though she prefers to let her sister do as she pleases.

An engineer for the Demon Army. An elf and Sera's younger sister. Even back in the elven forest, she was a troublemaker who loved machines, but her high level of ability led to her recruitment by the Demon Army. She is the creator of General Rivet. While she technically holds the rank of Vice-General, she has no interest in leadership and just wants to spend her time freely building robots. She sometimes assists Sera by turning the wounded into cyborgs or participating in her sister's schemes. She gets along well with Sera, but since both are extremely independent, they don't often show much outward emotion toward each other. She implemented an AI function for General Rivet to allow him to speak, though the AI uses a very peculiar tone. While she is an expert at repairing broken machinery, she gets quite irritated when work piles up unexpectedly.

One of the Four Heavenly Kings of the Demon Army. A robot with specs entirely focused on power and durability. Developed by Maniol. He is designed to operate autonomously even without Maniol present. Maniol, finding meetings tedious, implemented an AI function that allows him to participate in conferences naturally. However, he sometimes struggles with complex communication, leading Maniol to take over his tasks. He is slightly weak against the summer heat.