The infamous series of unexplainable murders in Hinamizawa have been solved and the chains of fate have broken due to the efforts of Rika Furude and her friends. Rika believes she has finally obtained the normal and peaceful life she desired with her friends; however, she is proven wrong when the wheels of fate begin turning once again after an unfortunate accident. Rika suddenly finds herself in a "perfect" world, the constant cycle of brutal killings having never taken place, where all of her friends are content and satisfied. Not wanting to abandon the world that she fought so hard for, she learns she must destroy an essential "key" to get back. But can Rika abandon the faultless world she is given the chance to live in, after all of her battles have brought her this far?

The story is set in the year 311 of the Orbital Calendar, when humanity has migrated to countless colony clusters in space. A space colony girl named Akiha Shishidou encounters a malevolent artificial intelligence named Leopard that has been installed on a colony. Akiha is joined by an Inter-Colony Police officer named Itsuki Kannagi, a taciturn young girl named Honoka Kawai, and a robot named Imoko "Imo-chan" Shishidou.

These are a series of 13 omake episodes of Gun x Sword, tied in very loosely to the plot, with the characters as chibi puppets. The main characters are Wendy and her turtle, Kameo, who is the size of a human in this series and is able to talk. All the episodes seem to center around analyzing various events in Gun x Sword and mocking the themes displayed. They are included on the DVDs.

Short specials added to DVDs and Blu-rays.