The social and political reforms implemented by Reinhard are finding growing consensus among the citizens of the Galactic Empire. Meanwhile, the Free Planets Alliance is experiencing a declining phase, its national power weakened significantly due to widespread government corruption, despite military success has been achieved on the battlefields. As the balance of power between the two super states dominating the Galaxy is clearly undergoing a major shift, Adrian Rubinsky, the Landesherr of the autonomous and nominally neutral dominion of Fezzan, sees an opportunity to take advantage from the situation.

In Raja, a small country located to the west of Tempest. Rimuru and his companions get involved in a long-running conspiracy that swirls around the mysterious power of the queen. Rimuru and his commander Benimaru also encounter another ogre survivor named Hiiro, a man that used to be the brother of Benimaru.

On her way to school one day, Suzume Iwato stumbles upon Souta Munakata, a young man searching for abandoned areas. The high school girl directs Souta to a nearby ruin, but out of pure curiosity, she herself decides to head to the same destination. Once there, Suzume discovers an isolated door with a dreamlike universe lying beyond it—a place that she can see and feel, but not enter. A strange stone rests on the ground nearby, but it turns into a cat-like creature and scurries away when Suzume lifts it. Suddenly afraid, she heads back toward her school, not realizing that her act of leaving the door open will have consequences. With the "keystone" released, the evil within the other universe can now freely escape and wreak havoc throughout Japan. Intending to correct her dangerous mistake, Suzume joins Souta—whose true goal is to prevent evil from festering—in finding and locking all open doors before the country is destroyed.

After vanquishing another boss and stepping through the gates of the fifth floor, the misfit duo Kazuto "Kirito" Kirigaya and Asuna Yuuki are greeted with a beautiful landscape of crumbling ruins and catacombs steeped in mystery. This idyllic adventure is short-lived, however. Tensions between the Dragon’s Knights Brigade and the Aincrad Liberation Squad—the two leading guilds focused on clearing Sword Art Online—continue to rise and threaten the fragile stability of the frontline raiding group. Kirito and Asuna are forced to act quickly, making a desperate gamble and gathering a small number of allies for a dangerous mission. As a result, Asuna and Misumi "Mito" Tozawa must come to terms with their relationship after the near-tragedy that forced them apart on the first floor.