As a maid, her creed is "duty before self". 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. Because of this, the other students seem to have strong trust in her, and she tends to wait outside the dormitory in case anyone has any requests for her. She is also shown to be very considerate and often asks the others if they are doing all right and gives them some advice. Her concern and kindness is often described as "motherlike", with Kokichi Oma even asking her to be "his mom". However, being a high school student, Kirumi completely denies such comparisons.

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.