Yuuji makes the unexpected decision to pursue promotion within the institution he works for. He meets with JB to discuss the documents he submitted for review as a part of the promotion process, documents pertaining to his own past.

Asako's poor health begins to interfere with her work. Yuuji senses her change in condition, and as he covers for her, he starts to think he may have found his life's meaning. Asako tries to respect Yuuji's resolve, but JB, who watches over both of them closely, is apprehensive about Yuuji's attempts to return to that violent world.

Yuuji goes to America to follow the same path as Asako, and through his rigorous military life meets and forms a deep bond with war buddies who go through the same joys and sorrows.

The Mihama girls have executed their intense getaway and have rescued Yuuji. Waiting at their goal is Kazuki Kazami, who lived as the core of Thanatos for a long time. This unexpected encounter leaves Yuuji and Amane unable to hide their surprise, but circumstances don't allow them time to savor their emotional reunion.

Tartarus, a gigantic, man-made island, floats on the Pacific Ocean. It is both the adversary of society, and the castle of Heath Oslo, Yuuji Kazami's mortal enemy. Oslo quietly awaits the moment Yuuji Kazami, the final key he needs to fulfill his ambitions, appears before him once more.