Hinata, Yuri, and Ooyama try to return to the surface from the underground tunnels (Guild) while the "final boss" (Shiina) tries to "kill" them. On the way, the three get ready to defend themselves by choosing weapons; Hinata - a 3-meter pike, Yuri - a Medieval sword and a katana, Oyama - a flail. Yuri tells Oyama to light the path forward with the flashlight they brought with them. While they walk, Shiina mysteriously appears, attacking the three, but Yuri manages to block the fist strike. Hinata tries to stab Shiina with the pike, but she retreats back into the shadow. Oyama frantically searches for Shiina, who then appears behind them.
Hinata is able to fend her off again, but Oyama is then assaulted by her next attack. Hinata and Yuri are able to have Shiina retreat again, not before Oyama spikes himself in the back with the flail. Then they decide to focus on retreating while Hinata guarded their rear. But when they climbed to the Level above them, Oyama gets his wrist (unknown which one, presumably his right) chopped off and loses the flashlight. While Oyama looks for it, Hinata guards them, tracing Shiina's movements with the pike. Yuri then blocks a throwing knife that Shiina threw at Hinata. While lunging forward, Hinata misses, and Yuri urges him forward to the surface. The next levels of climbing felt timeless, as Hinata and Yuri defied their bodies' urge to rest.
They finally manage to get out of Guild, all of them injured in some way. When they arrive at the school, Oyama reveals his wrist reattached itself. Yuri throws the now broken swords in fatigue, only to have Shiina appear above them on the roof railing, which she gets their attention by saying "how shallow-minded". Shiina strikes at Yuri, but Angel comes to defend the tired Yuri, both Hand Sonics at her forearms. Yuri issues a retreat, smiling. Hinata wonders if Angel was part of her plan. Yuri tells them to look for Chaa and Noda. While they search, Yuri decides to establish the battlefront against God. With 4 members, she comments that is enough for the battlefront. Hinata thinks in his mind that this was what the real Yuri would do. Then Yuri tells Oyama that he no longer needs to hold the flashlight anymore, which he embarrassingly throws to the ground.
When they find Noda and Chaa, Noda is lying on the ground, beaten badly by Chaa, commenting that Chaa is just too strong for him. Yuri tells Chaa about the Shinda Sekai Sensen (Afterlife Battlefront), telling him that he and Noda are already members. Noda complains about this, first about the battle not being over, then because of his comparison of "weakness" to Chaa's "strength" and "mean personality". Oyama asks Noda why he ran away, to which Chaa replies it was because of Hinata and Yuri's "relationship", to which they deny. After a while, Noda stands up with his halberd, declaring that he will become Yuri's sword, but he winces as he realizes that the "final boss from underground" was his enemy.
As the five watch Angel's and Shiina's battle, Noda asks about Angel's blades, to which Yuri replies that it is Angel. Noda asks questions of the battle to which no one decides to answer. Yuri and Chaa comment on where the battle is going nowhere, as Angel has strength to compensate Shiina's speed, and brings it all down to endurance. Noda then makes the point of the battle not focusing on endurance as it is between an angel and a "final boss", both of which have no limit to endurance. Yuri then declares that once Shiina was recruited, the SSS would have reached its peak, and that she has become the leader to issue orders. Chaa and Noda are ordered to help Angel, to which Noda lifts up his halbeard and Chaa picks up Oyama's fallen flail. Oyama is instructed to keep track of Shiina's position until she is driven to the wall of the school.
Hinata and Yuri are on the roof, waiting for Oyama's signal. Hinata is standing in front of the rail with the two broken swords. They talk about the previous times about Yuri kicking Hinata over the railing. Hinata asks her about the plan, being just over Shiina, and Yuri tells Hinata to go just as Oyama signals with waving his arms. When Hinata finally realized it, he was kicked down... again. Falling 15 meters toward the ground, he saw through his near-closed eyes that Shiina was at where he was falling to, and through this, he falls, and the swords slice Shiina in half. Hinata did not escape pain though as he collided into the ground. Before he loses conscience, he comments that the first operation of the SSS was finished... and a success.
Hinata wakes up in the infirmary, where Yuri interrogates Shiina (who is mummified in bandages at the moment on the next bed over from Hinata), but Shiina remains silent. Oyama finds Hinata awake, who comments on his cleaving of Shiina in half. Hinata tells him not to make him remember, then learns that Shiina refuses to speak. When Yuri proposes Shiina's joining to the SSS, Shiina agrees with a nod of her head. Noda becomes appalled at the idea, to which Yuri answers with not to ask about future member's pasts. She also goes to the conclusion that members desire vengeance against God that forces their destinies onto them. Yuri then tells Shiina that Angel is the only enemy to face. Shiina then speaks, saying that she wants to rest, and then asks about what an ally is when Yuri says the SSS members will protect her. Yuri asks for her name before she would rest, but Shiina succumbs to sleep beforehand.
Yuri then proposes to make an SSS headquarters, deciding the opportune place to be the Principal's Office, and giving the Principal a seat in the staff office. Yuri decides to make an Anti-Angel trap that includes Angel to knock on the door and be flattened by the trap. She puts Noda in charge of the task. Chaa ridicules Noda, whom tries to start a fight if Oyama hadn't tried to break it up. At this moment, Hinata comes up with the term "NPC", to which Yuri says that she'll use to address the teachers and the students. In the end, Hinata says in his heart that Yuri is their leader, no matter what happens.