She was voice-acted by Ami Koshimizu.
She has superhuman abilities and appears to be some kind of humanoid interface along with Taiichirou Ijuuin. The two appear interested in Haruhi Suzumiya and sometimes act with hostility toward Kyon and Yuki Nagato.
During at least one confrontation, she and Ijuuin change their outfits to a purple sci-fi ensemble.
At the end, the SOS Brigade returned to their headquarters, and didn't pay attention to a white hat sitting in the room. After they left, Kyon returned to the room, when Misumaru appeared there. She put on the hat and said her farewells before vanishing (appearing to disintegrate). Shortly thereafter Haruhi entered the room.