As a honey trap infiltration assassin, Irina is a very seductive person. Her flawless acting skills allow her to adopt any personality that might benefit her in her mission. This allows her to execute her targets at point blank. As a killer, she's ruthless and always achieves her objective. Her extreme resilience is one of her most dangerous aspects as a hitwoman, since no matter how many times and ways she has to try, she will ensure her target is dead.
Outside of work, she's shown to be a surprisingly normal, even clumsy person. The luxury lifestyle she lives in as a high class hitwoman made her lose touch with the everyday world. At times, her attitude seems even childish and extremely unprofessional, much to the chagrin of Karasuma.
Her true self, however, is extremely insecure and unstable. She has little to no trust in people, and seems to be afraid of her own feelings. Her traumatic memories from childhood never left her, and thus she didn't grow up properly as a person. She had shut off her feelings completely to be able to perform her job properly, and became afraid she might not be able to live that life anymore upon realizing how much she cared and truly felt about the students and especially, about Karasuma.
After the God of Death incident which forced her to confront her traumatic past, Irina has since acted more professionally and much less arrogantly than before. She is more subtle in seducing people with just her facial beauty such as attracting delinquent students to do what she suggests during the school festival. However, she is still prone to being mildly immature, for instance giving inappropriate sexual answers in a mock parent-teacher interview (almost causing Megu Kataoka to stab her in rage).