The 3rd Gear makes its move! The Hecatoncheires, automatic combat-type dolls, have set their sights on Mikage, forcing the participants of the Leviathan Path to enter the battle. As if that were not enough, a third force begins to stir โ a mysterious group with the telling name Army. Meanwhile, Tsukuyomi Miyako, having found herself either captive or a guest in some ancient palace, though surrounded by the care of automatic maid dolls, gradually begins to learn the terrible and tragic past of the 3rd Gear, which gave rise to the mysterious Impurities...