After the events of the second season, Ai's three helpers, Ichimoku Ren, Wanyuudou, and Hone-Onna live out their lives in relative peace. This is suddenly shattered when Kikuri returns to recruit them. Meanwhile, Ai mysteriously reappears from the dead and uses the body of a young schoolgirl, Yuzuki Mikage, to continue the Jigoku Tsuushin operation. Yuzuki is aware of Ai's presence, however, when she can see what Ai sees. (myanimelist.net)