The ninth volume of the Sora no Otoshimono manga was first released on September 9th, 2010 by the Kadokawa Shoten Publishing Corporation. This volume introduces a new character by the name of Hiyori Kazane to the story that becomes deeply involved in the lives of Tomoki and his friends as they get back to a normal life after the end of the Chaos saga.
Chapter Thirty Five: Purity
Chapter Thirty Six: Doubts
Chapter Thirty Seven: Hiyori
Chapter Thirty Eight: Forgetfullness