Irisu's personality is somewhat adaptable depending on her goals and the situation, though it should be noticed that she is almost always outwardly shy. Though she does not speak outside of her diary, it is obvious that something is unusual about her. In the bad ending, she falls for Uuji's plan -- ultimately murdering Uuji himself and the two others. The death of the rabbit in her childhood (also a deed executed by Uuji) possibly could have caused her to become unstable and murderous and insane