An original story included with volume 10 of the Nakanohito Genome [Jikkyouchuu] manga.

Extra episode of Nagato Yuki-chan no Shoushitsu bundled with the limited edition of the 9th manga volume.

Years of political tension and mistrust between the two rival nations of Zafran and Revillia escalate to the point of war. Each nations solution: to gain possession of Decimators, the same ancient robots of war that nearly ended all life on the planet 200 years before. As the war ensues and the leaders of both nations become reluctant to surrender, only the desperate plan of Lean, a young cadet, and Nataruma, a psychically gifted young woman, to alter the timeline of events 200 years before stands the chance between humanity's survival or absolute destruction.

The characters from previous .hack//G.U. Games and .hack//Roots receive an email from Ovan. He is requesting them to go to Hidden Forbidden Festival where is set up a mysterious summer festival. There they find an AIDA Chim Chim who wishes to peacefully co-exist with the other players of The World. It then transforms into the word "Returner", so they assume it to mean that Ovan will return to The World.