This special follows the story of how Isaki Shuuji and Ruo Minai became Contracted Priest and Shikabane Hime.

Rikka Isurugi has spent her life training in the way of the ninja with her grandfather Hyoe while following in the footsteps of her father, the esteemed researcher Allen. His work has culminated in a set of cutting- edge drones equipped with artificial intelligence and incredible technical capabilities; although Allen plans to develop these drones for civilian use, there are others who have more sinister ideas in mind.

On Rikka's 16th birthday, things are forever changed when a paramilitary group raids the Isurugi house in search of the drone technology, killing Allen and Hyoe while Rikka manages to escape with the drones. Months pass, and Rikka is now an ordinary girl working as a private detective while sharing an apartment with another girl, Melissa. But when night falls, she dons her grandfather's fox mask and mercilessly hunts down those responsible for the attack. With the anger she felt that day driving her forward, Rikka will not rest until her family's killers receive the justice that they deserve.

[Written by MAL Rewrite]

Recap of the Aoki Hagane no Arpeggio: Ars Nova TV series, with approximately 40 minutes of new material. By 2039, global warming had caused sea levels to rise and large amount of territory to be lost. As though in response, a mysterious group of warships clad in mist, "the Fleet of Mist," appeared in every corner of the ocean, and began attacking human ships. In spite of humanity mustering all their strength, they were utterly defeated by the Mist's overwhelming force. All of humanity's trade routes were blockaded by the Fleet of Mist, their political economy was destroyed, and the human race was steadily beaten down. Seven years later, the Fleet of Mist's submarine I-401 appears before cadet Gunzo Chihaya. The humanoid life form that pilots the sub, who should be their enemy, is instead offering her services to mankind. (Source: ANN)

The group of privateers known as the Blue Steel continues their mission to deliver blueprints of the Vibration Warhead Torpedo—a weapon that may turn the tides of war in their favor—to the United States. However, a new threat arises from their enemy, the overwhelming Fleet of Fog in the form of "The Student Council.," This is a group of warships composed of the remaining Mental Models—the ships' humanoid avatars—who have yet to face the unpredictable captain of the Blue Steel, Gunzou Chihaya. As the Blue Steel gets closer to understanding the origins of the authority controlling the enemy, Iona's past starts to reveal why the war began and her reason for siding with humanity. [Written by MAL Rewrite]