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.