The sixth volume of the Sora no Otoshimono manga was first released on September 26th, 2009 by the Kadokawa Shoten Publishing Corporation. This volume introduces the Man of Synapse's newest and most powerful weapon in his war against Tomoki, Ikaros, Nymph, and his friends: Type Delta Close Combat Angeloid Astraea.
Chapter Twenty Three: War
Chapter Twenty Four: Investigation
Chapter Twenty Five: Out of Money
Chapter Twenty Six: Supplementary Lessions
[Extra Chapter] The First Excavation