A woman that was kind to her. Ai, being used to the kind people of Mayfield by now, was quickly befriended by the woman. However she was hired by the town to guard the highway during an event and showed her true colours when she gassed and killed Ai with no regret.

Ai re-learned a valuable lesson from that. You can't trust people. Especially humans. She lost a great deal of trust in humanity from the experience. However sought no revenge. She trusted the woman and that was her own fault for doing so. In her mind, she will get revenge when the woman died and will no doubt go to Hell for her life's actions. Ai likes to believe she's there right now.