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 has a free-spirited personality, ignores social cues, and doesn't care about the means to an end. Due to this temperament, she has the power to be one of the Four Heavenly Kings, but she has absolutely no interest in the position. Her problematic behavior is quite noticeable—turning the wounded into undead, interfering with the Demon Army's authority, and forcing people to undergo health checkups for her own 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 in the Demon Army. An elf and Sera's younger sister. Even back in the elven forest, she was a troublemaker who loved machinery, but her high level of ability led to her recruitment by the Demon Army. She is the one who created General Rivet. While she technically holds the post of Vice-General, she has no interest in leadership and just wants to be free to build robots. She sometimes assists Sera by turning the wounded into cyborgs or participating in her sister's problematic schemes. She gets along well with Sera, but since they are both extremely independent, they don't express much emotion toward each other. She implemented an AI function to allow General Rivet to speak, but she programmed the AI to use a very peculiar tone. She is also skilled at repairing broken machinery, but she gets quite irritated when work piles up unexpectedly.

One of the Four Heavenly Kings of the Demon Army. A robot whose performance is entirely focused on power and durability. Developed by Maniol. Built to operate autonomously even without Maniol's presence. Because Maniol finds meetings tedious, she implemented a function that allows the robot's AI to handle conferences naturally. However, since communication can sometimes be difficult, Maniol is often forced to take over the work anyway. He is a bit weak against the summer heat.