Who raps on the narrator's basement window in Chapter 4 and for what purpose?

In Chapter 4, the narrator is surprised to find Professor Inui, a friend of her late father's, standing with his family outside her basement window. After they all get inside, Professor Inui explains that he has been summoned by the Memory Police and that he believes that they want to use his research in order to isolate the gene that allows some people to evade their methods of control. Before they go into hiding, they wanted to bring to the narrator the five sculptures that her mother had given them throughout their friendship.