After Ai Enma's supposed death after the events of the 2nd season, her 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 Tsūshin operation. Yuzuki is aware of Ai's presence however, when she can see what Ai sees.

[Source: Anime News Network]