Kirumi is a refined, mature young lady who's described as "a professional who does a perfect job". She has a keen mind and she is talented in various ways, reportedly able to carry out any job, as well as capable of being independent and do things on her own. She is polite and formal, as well as quite serious, and very willing to use all of her power to cooperate with the other students. She is intelligent and level-headed. Her intelligence can be shown when she is speculating. As a maid, Kirumi's creed is "selfless devotion". Thus, she has a very strong sense of duty and a will to work for the sake of others even during the Killing Game. She voluntarily does house work such as cleaning and preparing meals for the students, even making sure each time that there's both Japanese and Western cuisine.

On the other hand, Kirumi lacks the concept of doing something for herself, and for her even to have a conversation is a request. She believes her own opinions hold no importance. Despite her sense of duty, she does have a limit to what she is willing to do, declining requests such as destroying a nation, giving sexual services, or unfairly removing someone who hasn't done anything wrong from a public area. She has stated that while she is a maid, she is not a slave.