Momoko Kunieda is a supporting character in The Perfect Insider. She is an architecture student at N University who assists Souhei Saikawa with his accounts and administrative tasks. Her appearance is androgynous, with short black hair and a boyish look, and she maintains a nearly expressionless face that gives her a perpetually moody or unapproachable demeanor. She speaks in a direct, straightforward manner that many other students find intimidating, leading them to fear her and keep their distance. Despite her outward seriousness, she tends to show little active interest in the murder case that unfolds around her, remaining more of a quiet observer and occasional helper rather than an active investigator. Her primary role in the story is to support Saikawa and to serve as a familiar face in his academic circle, providing background context to the dynamics among the university group. She does not undergo significant personal development over the course of the series, nor does she demonstrate any exceptional analytical or physical abilities beyond her competence as a student and assistant. Her relationships are limited mainly to her professional interaction with Saikawa and brief exchanges with other characters such as Moe Nishinosono and Fukashi Hamanaka.