Attack of the Wolf - S1.E6

Ryuji, Eriko and Rose were attending a party with many A class and above Lost Preciouses. They also meet a new collector who seems interested in Eriko; he tells her that if he finds out anything about her other earing then he will contact her. The guests were attacked by "Odd Eye", a half-beast Lost Precious thief that Ryuji had just seen in a magazine. Later at their home, she tried to steal Eriko's earring, but end up tied to Ryuji by a failed capture device. While waiting for the bind to vanish, they learn that her true name is Ai, and try to figure out who is making her steal, and why. The next day Eriko answers a knock on the door and it is the new collector who says he has found the other earing. He opens the box supposedly containing the earing and sleeping powder comes out of it, putting Eriko and Rose to sleep. He then tells Ai to follow him, putting Ryuji to sleep as well.