Ikaros (Ikarosu), first introduced as a “Pet-Class Angeloid, Type Alpha”, becomes bonded to Tomoki at the beginning of the story doing a “contract” with him called Imprinting symbolized by the invisible chain leading from her collar to Tomoki’s hand.
Sora no Otoshimono began monthly serialization in the May 2007 issue of manga magazine Shounen Ace. The first tankobon was released by Kadokawa Shoten on September 26, 2007, with a total of 16 volumes released as of October 26, 2012.
An anime adaptation produced by AIC aired in Japan in 2009,followed with a second season, a feature film, and two video games.
A third anime season is in development for 2013. The anime is licensed in North America by Funimation Entertainment.