Who is Ayumi from 1Q84 and what is their importance?

Ayumi is a twenty-six-year-old police officer. Over the course of the novel, she and Aomame become close friends due in large part to their similar experiences. Ayumi, like Aomame, was sexually abused, experienced that leave both of the girls seeking love and sexual satisfaction in all the wrong places. Shortly after Aomame distances herself from Ayumi, Ayumi dies under questionable circumstances.