Shizuku Kurogane vs Wallenstein

Shizuku Kurogane vs Wallenstein is a battle between Hagun Academy student Shizuku and Wallenstein, who is one of the Numbers of Rebellion, which happened during Nagi's retrieval.

Prologue
Akatsuki Academy ambushes Hagun Academy and Reisen Hiraga, uses the opportunity to capture the traitorous Nagi, who had betrayed their original plan and bring him back to Akatsuki Academy for punishment. Shizuku quickly follows the two and had eventually been run down by Ikki who decides to help her. Shizuku and Ikki then get on a bike and arrive at Akatsuki Academy. Shizuku leaves her brother to fight an unknown enemy as she rushes in to save Nagi from an agonizing fate.

Wallenstein is seen talking with Nagi and asks him why he had betrayed him. Nagi had thought to himself that he could not throw away his emotions nor throw away the girl he cared for. For that reason, he had betrayed Akatsuki. He had then undone his restraints and attacked Wallenstein only to be overpowered by him immediately. Wallenstein realizing that he had lost his student forever, decides to allow Nagi watch as he takes everything away from him and at that moment Shizuku appears.

Nagi asks why she had come for him even though he begged her to leave him to which she responded that they are friends. Nagi then realized that his fear of Shizuku's hatred for him had been for nothing as Shizuku still cared for him even after finding out about the truth. Sickened by this revelation Wallenstein knees Nagi's back and decides to kill Shizuku.

Battle
Shizuku quickly pulls out her device and conjures an ice hammer and launches down on to Wallenstein. Wallenstein, however, is undeterred, as he continues his encroachment on to Shizuku, who quickly used Toudo Heigen, creating ice along the ground to reduce her opponents agility and then quickly used Keppu San'u creating balls of spiked water. Shizuku fired all of the spiked water balls at Wallenstein but to no effect, even Toudo Heigen's ice floor had no effect whatsoever on Wallenstein. Shizuku had readied herself using a protective wall of ice to shield herself, however, Wallenstein used Bergschniden, to easily cut through her defenses.

Shizuku was able to dodge Wallenstein's attack, but at the price of her own arm in the process. Shizuku then uses Byakuya Kekkai, raising a veil of mist to cover Wallenstein's vision, and began to run around in the mist. Wallenstein having grown tired of this tactic planted his sword to the ground, and Shizuku had begun to slip realizing that Wallenstein's ability is to take away friction. Wallenstein finally stands before Shizuku and cuts her waist.

Shizuku who had indeed been cut in half decides to try a new technique, being only seconds away from dying, which she developed after her match with "Raikiri". Just as Wallenstein began taunting Nagi, Shizuku's body had disappeared leaving only her clothes. She then begins to speak with Nagi, causing both Nagi and Wallenstein to scan the area to try and find her. Shizuku finally appears and Wallenstein cuts her again, only to find that Shizuku had turned her entire body into vapor, which Shizuku named Aoiro Rinne. Shizuku's Aoiro Rinne allowed her to control the air that Wallenstein was breathing to drown Wallenstein. Wallenstein begged for Shizuku to spare him but Shizuku only smiled and snapped her fingers causing multiple ice spikes to pierce Wallenstein from the inside, with blood coming out from all over Wallenstein's body.

Epilogue
Shizuku then finds Nagi, and they once again enjoy each other's company as though they truly were relatives. Kurono comes in and notices a bizarre magic presence. She then deduces that Shizuku was somehow able to reconstruct her body. It is later revealed that Nagi had decided to drop out of the tournament because of this incident, but Shizuku was allowed to enter the tournament knowing the dangers that lied in it. Wallenstein also survived the encounter and escaped through unknown means.