Mayumi Kisaki is a supporting character in The Devil Is a Part-Timer! She is the manager of the Hatagaya branch of MgRonald's, the fast-food restaurant where the main character Sadao Maou works. In her late twenties, she is a tall, fair-skinned woman with dark violet hair and blue eyes, and is considered highly attractive by some characters. As a manager, Kisaki is strict and no-nonsense toward her employees. She does not hesitate to issue intimidating warnings to Chiho Sasaki about her frequent work accidents or to pressure Sadao Maou to perform well, especially when the branch faces competition from a rival company. Despite her severe demeanor, she is a competent and professional leader; even Maou, a former demon lord, respects her as a role model in the workplace. Kisaki's primary motivation is to run her branch successfully and meet corporate expectations, which often puts her at odds with the more relaxed or distracted attitudes of her staff. Her role in the story is largely that of a workplace authority figure who provides a grounding, real-world perspective amid the supernatural events, and she interacts regularly with Maou, Chiho, and Emi Yusa in her capacity as their boss. She does not undergo significant character development, remaining a consistent and dependable figure throughout the series. Her notable abilities lie in her managerial skills, her ability to keep order in a busy fast-food restaurant, and her capacity to be surprisingly intimidating when asserting her authority.