Izuru Kira vs. Makoto Kibune

Prologue
Izuru is seen waiting outside of the Kasumiōji compound, believing it to be the place where Kibune is most likely to be hiding. As he does so, he also believes that Kibune won't dare approach, as the Gotei 13 have been running in and out all day. He decides to search elsewhere, and comes across a Hell Butterfly, which approaches him, stating that Amagai is with Ichigo Kurosaki, and is notified that there is a conspiracy within the Kasumiōji clan. After his brief conflict with Amagai, Ichigo asks him what they are going to do, to which he informs them that he is going to check out several places with them, returning his subordinates to the 3rd Division barracks.

He continues, stating that he only requested Aida and his group to assist them. Ichigo wonders why Amagai is so persistent in helping them, to which he says he has his own reasons. Rukia asks him to tell her those reasons, which he states he will do so, so long as they are in a safer area. As they do so, however, two Shinigami from the Seventh Division are eavesdropping, and try to report this to Captain Komamura. As they run, Amagai explains that his 3rd Seat is Kibune, and reveals that he has an association with the Kasumiōji Clan. Rukia wonders if Kibune's involvement is related to their predicament.

He informs them that he assigned Kira to keep an eye on Kibune. He also says that Kibune is his responsibility, as he was the one who chose him as 3rd Seat, even going as far as to say that he'll take care of him personally if it comes to that. Shū asks them if they know where Rurichiyo is, to which Amagai says they'll search all of the buildins within Seireitei that are affiliated with the Kasumiōji clan. Meanwhile, a messenger relays Komamura's message to Yamamoto, who assumes that Shūsuke Amagai is a traitor, and as such, must be apprehended, and notifies all squads, hereby calling an emergency captain's meeting.

Aida and his group report in, stating that there is nothing suspicious to be found, but hear reports about Amagai's affiliation with the Substitute Shinigami. They wonder whether Amagai will be alright, as it was always either Kira or Kibune's job to know about the captain's motives. Kira is seen searching in a warehouse, and comments upon the convenient disappearance of Kibune when the crisis began, wondering whether it is related to Ichigo's involvement. As he leaves the warehouse, he resolves himself to find Kibune as soon as possible.

He remembers back to their training session, and that Kibune was the one who arranged for the use of the training ground. Kira realises that he is hiding there, solely because no-one cares about it. Izuru runs off, believing it to be the only lead in finding Kibune. Yamamoto commences the captains' meeeting, stating that Ichigo and Rukia should be apprehended alongside Amagai, who acted as their accomplice. However, Ukitake is quick to come to their defence, stating that their actions are questionable. He requests Yamamoto's permission to investigate the Kasumiōji clan,which Yamamoto denies, telling all divisions to act upon his orders only.

Kyōraku and Ukitake believe that the Kasumiōji clan is central to this entire problem, and believe that the Gotei 13 will fall apart if the dissension continues. Nanao interrupts their conversation, informing them of the several fights occurring across Seireitei. As the fights continue, Kira comes across several other divison members standing over a brown blanket. Kira asks them what is wrong, to which they reply that this is the body of Sugama, who went missing last night. Kira recognizes him as the Shinigami who was sent to search for Kibune. Kira then runs in the direction of the training ground.

As Izuru enters the training ground, he hears faint footsteps echoing from above him. Rurichiyo is seen fiddling with the lock on her cage, and to her surprise, it opened. She steps eagerly out of the cage, and is instantly confronted by several of the assassins, who proceed to put her back in the cage. As Izuru watches from above them, and wonders who the men are, upon realisation that they are keeping Princess Rurichiyo from the Kasumiōji clan captive. He sends a Hell Butterfly to Captain Amagai, informing him of the situation, just as several daggers are thrown at him, which are deftly deflected by his sword.

The assassins quickly surround him, and their apparent leader signals for them to converge upon him, but Izuru is able to overpower them with ease. As Izuru confronts the leader, he started laughing in a mocking tone, stating that it is the other way round. Before Izuru can react, more of the assassins appear, as the leader equips his Bakkōtō, causing orange reiatsu to flow into the sword. The assassins then take this as their cue to strike, as one is able to successfully knock him back, as he seeks refuge in the main arena of the training ground, and is instantly surrounded.

As Izuru struggles to ward off the group's efforts, he wonders how their reiatsu inexplicably increased. However, he hears the struggling cries of Rurichiyo, who is being dragged away by another assassin. Izuru tries to stop them from taking her away, but is quickly surrounded by assassins, preventing him from moving forwards. He manages to push them away, and charges towards the main group of assassins. He manages to defeat them all, but the effort has pushed him to his limit, as he pants heavily. He shrugs off his injuries, attempting to follow the assassins, but as he does, a spinning blade approaches him, cutting him off from the exit.

Battle
Izuru uses Flash Step to avoid the attack, and turns to face off against another attck from the spinning disc, which he effectively evades. Kibune then comments upon the slow nature of Kira' movements, and affirms that Rurichiyo is long gone, to which Kira realises that he was the main mastermind behind the Kasumiōji conspiracy. Meanwhile, Amagai goes with Ichigo to help rescue Rurichiyo, Rukia protecting Shū, and Aida and his group moving out to assist Kira. .

Meanwhile, back at the training ground, Kibune commends Kira's prowess in dodging his attack, stating that he is worthy of the title Lieutenant. He stares down at the assassins, telling him that, although they were low-olevel fighters, he decided to give them Bakkōtō, as their bodies evaporate into nothing. Kira then asks whether he is allied with the Kasumiōji clan, to which he laughs, telling Kira to die. He then sends his Zanpakutō hurtling towards Kira, proceeding to repeatedly attack the Lieutenant.

Suddenly, Aida's group appears, much to the surprise of the two combatants. Aida asks why they are fighting, and confirms the whereabouts of Amagai, much to Kira's relief. He tells them to stay back, claiming that Kibune is now their enemy. The group then asks for Kibune's opinion on the matter, to which he replies that he'll kill them all. He turns his Zanpakutō,Reppū, into a spinning blade, and proceeds to attack the three Shinigami. Upon realising that his threats are real, they dodge in the nick of time as Kira tells them to leave. As Reppū circles back for a second attack, Kira intervenes, releasing the powers of his own Zanpakutō, Wabisuke, effectively blocking Kibune's onslaught.

Kibune boasts that Kira's "squared hook" can't possibly stand up to his own Zanpakutō's power, as Izuru swings Reppū back to its owner. As Kibune grasps his Zanpakutō's hilt, it instantly plummets to the ground, as a side effect of Kira's Zanpakutō. Kira tells him that he can no longer use his Zanpakutō, and asks him what he hopes to accomplish by siding with the Kasumiōji clan. Kibune states that what the Kasumiōji clan does is none of his concern, but reveals that he wants to use their vast power to become the strongest Shinigami.

Suddenly, his Zanpakutō glows green, and to Kira's surprise, it lifts off of the ground, regardless of the effects of his sword. He clashes with it in midair, shortly before it hurls him into the base of the training ground. Kibune starts laughing as he retracts his Zanpakutō, as Kira is seen struggling on the ground. He wonders why Wabisuke isn't working, as he attempts to hide from Kibune. Kibune tells him to stop hiding like a coward, as Kira asks him why someone strong like him isn't satisfied with his own power.

Kibune runs out to the alcove, and finds Kira, sending Reppū hurtling forwards, with Kira dodging it easily. He then uses kidō, which catches him off guard, causing him to crash to the ground; dislodging his glasses. Kira lunges at Kibune, who calls out to Reppū. Kira says that it is too late, but Kibune reveals his left arm, which is draped in his Bakkōtō, which releases green reiatsu, causing Kira to get thrown backwards. Kira balances himself, but he is no match for Kibune's superior speed, and ends up outside on the floor of the training ground.

Kibune walks towards him, as Kira stands up once more. Green reiatsu flows from his Bakkōtō, as his reiatsu is sucked away, causing Kibune to groan in pain. Kira asks what sort of weapon is that, to which Kibune replies it is a Bakkōtō, and that it will evolve without limit due to his reiatsu. Kibune states with spite that he was always looked down upon, even during his days at the Shinigami Academy. When he was finally granted entry into a squad, he was reprimanded for not caring about the lives of others when he fought, even though he was exceptional in his abilities.

Kibune then states that the power he has isn't enough, that he will force every last Shinigami to bow down to him. Kira realises that the katana is taking over his mind, as Kibune vows to remove Kira from his position as lieutenant. Kibune then proceeds to attack him, sending his Zanpakutō out mindlessly, as Kira dodges a multitude of attacks,before being smacked down to the ground. As Reppū begins to circle back towards him, Izuru blocks it at the last minute, sending him hurtling backwards. Izuru is then dealt a severe injury from the rotating blade, but he continues to fight him, much to Kibune's disbelief.

Kira releases his reiatsu, upon hearing of Kibune's plan to slaughter the entire 3rd Division, stating that he would not allow that to happen. He then faces off against Kibune, this time being able to see through most of his battle strategy. He fires kidō directly at Kibune, sending a plume of smoke rushing over him. However, Kibune emerges undeterred, as Kira states the power he obtained isn't truly his. He starts to overpower Kibune, eventually cracking the sheath on his sword concealing his Bakkōtō. As Kira does this, Wabisuke's power returns, causing Reppū to plummet to the ground once more.

Kibune refuses to lose, releasing more of his reiatsu into the Bakkōtō, as it wraps itself around his torso, thus becoming possessed by the katana. As this is occurring, Aida's group lapses from unconsciousness, and they witness the spectacle going on. Izuru vows to defeat Kibune, as the Lieutenant of the 3rd Division, as he charges towards him, resulting in his Zanpakutō getting shattered in half and his body consumed by fire, as his Bakkōtō slides away from his body. Kira faints shortly afterwards, as his companions look after him.

Aftermath
Meanwhile, Ichigo and Amagai are seen pursuing the lone assassin making off with Rurichiyo, and soon corner him. They tell him to give her back,to which he throws her in the air, in an attempt to catch Amagai off guard. However, Amagai does not fall for the trick and cuts him dow. Ichigo grabs her whilst in midair, and realises that it is just a doll. Rukia and Shū catch up, as Amagai receives a message to go to the training ground.