The New Captain of the 3rd Division

 is the beginning of the Kasumiōji Conspiracy, detailing the first mission that the Third Division is entrusted with shortly after Shūsuke Amagai is promoted to become their new captain.

Prelude
At the Tenth Division barracks in the Seireitei, Lieutenant Rangiku Matsumoto excitedly leans over the desk of her captain, Tōshirō Hitsugaya, and asks him if he heard that the Third Division is getting a new captain, prompting an annoyed Hitsugaya to remind her that he has already heard because he is a captain and continue filling out documents as he clarifies that the official announcement will be made at the captains meeting tomorrow. With Rangiku wondering when 3rd Division Lieutenant Izuru Kira learned to perform Bankai, Hitsugaya reveals that he is not the new captain.

Astonished by this, Rangiku slams her hands down on to the desk, causing several documents to fly off the stack next to her, and expresses her disbelief of this. In response, Hitsugaya admonishes her for scattering the documents and admits that he does not know much about the new captain, and when Rangiku asserts that she did not believe Izuru was suited to be a captain anyway while wondering who it will be if not him, Hitsugaya concludes that they will find out at the captains meeting tomorrow and orders her to get back to work, leaving Rangiku to continue pondering the situation.

The next day, in the meeting room within the First Division barracks, Captain-Commander Genryūsai Shigekuni Yamamoto informs the assembled captains that the Gotei 13's expedition unit returned after completing a long-term assignment and without suffering a single casualty, which he considers to be a great success. After bringing up the Third, Fifth, and Ninth Division lacking captains as something they cannot allow to remain unresolved, Yamamoto reveals that he summoned the leader of the expedition unit yesterday and deliberated over his capabilities as a captain alongside two other captains.

Concluding their decision was unanimous, Yamamoto announces that the new captain of the Third Division replacing Gin Ichimaru will be Shūsuke Amagai, who enters the room at Yamamoto's prompting. Meanwhile, on an outdoor pavilion in their quarters, the other members of the Third Division wait and discuss Amagai's appointment among themselves, where Inose observes that someone they have never even heard of is going to be their captain and responds to Aida pointing out Amagai has been absent for a long time on a Hollow-suppression expedition by asserting this does not matter when their captain will be a stranger.

The New 3rd Division Captain and the Uncertain Lieutenant
With Inose questioning if they can follow such a man, Aida points out that Izuru is no better while the latter arrives, greets the other Shinigami, and expresses hope that the new captain is nice, which leads Inose to concur with Aida about his unreliability. Back at the meeting room, Amagai walks between the two rows of captains as 7th Division Captain Sajin Komamura notices two sword hilts sticking out from his haori, which leads him assumes that Amagai wields two Zanpakutō, and 8th Division Captain Shunsui Kyōraku smiles at Amagai's solid presence. After coming to a halt, Amagai introduces himself.

A slightly stuttering Amagai requests guidance from the captains due to his inexperience. Shortly afterward, 13th Division Captain Jūshirō Ukitake informs Amagai that captains must deal with a lot of protocol and cautions him that it can be overwhelming to get used to at first, which is why Amagai should come to him if he needs help with anything. While Amagai thanks Ukitake for this and the other captains depart, Komamura inquires about who the other two captains who deliberated over Amagai were, only for Shunsui to question if it matters since an empty captain position has been filled, which they should be glad for, and Komamura agrees.

However, 2nd Division Captain Suì-Fēng interrupts Komamura and Shunsui to tell them that they will see how good Amagai actually is in time as 6th Division Captain Byakuya Kuchiki looks back at Amagai from the doorway before leaving. During this, in his office, Yamamoto responds to 1st Division Lieutenant Chōjirō Sasakibe commenting on a captain vacancy finally being filled by asserting that it means nothing when two more remain because a void causes discord at any time or place, which an evil being trying to display their power would exploit by targeting since such a void would be considered a vulnerable spot among a group.

Simultaneously, at the Third Division barracks, the assembled Shinigami are surprised when Amagai approaches with Makoto Kibune. When a chuckling Amagai asks the Shinigami for their lieutenant, Izuru steps forward and introduces himself, prompting Amagai to do the same, and the two shake hands before Amagai identifies Kibune as a fellow new member of the Third Division who formerly belonged to his expedition unit and was recruited as the 3rd Seat for his skill. While Kibune greets Izuru, Inose and Aida remained stunned by Amagai being their new captain due to his strange demeanor compared to the other captains, which Amagai notices.

When Amagai inquires about what is wrong, Inose speaks over an uncertain Aida to bluntly assert that the Third Division was doing fine without a captain until yesterday. Though Izuru demands that Inose stop, Amagai claps his hand onto Izuru's shoulder, tells the Shinigami that he knows how they feel, and assures them that it is natural to feel put off by someone they do not even know showing up to tell them that he will be their captain starting from today. With the Shinigami surprised by his insightfulness, Amagai steps forward and promises to protect them so long as he is their captain because this is a captain's duty and grins at them.

Later, Izuru sits with Rangiku in Hitsugaya's office, where Rangiku notes that he does not even know how capable Amagai is. Though he acknowledges this, Izuru clarifies that the problem lies with the rest of the Third Division feeling highly uncertain about Amagai and admits that he does not know how they will be pulled together and unified tomorrow. Rangiku expresses exasperation at Izuru overcomplicating a matter of his comrades simply teaching the cocky new transfer student a lesson, but Izuru counters that he is the one who will be caught in the middle of this, which leads Rangiku to deduce that he is nervous about the situation.

Walking over to Hitsugaya's desk, Rangiku pulls out several containers of sake for Izuru to drink away his worries with, and despite Izuru protesting that he cannot drink during the daytime, Rangiku declares that this is when it tastes best and suggests that Izuru hold a party with the rest of the Third Division in order for them to quickly befriend Amagai. After Izuru wonders if this is really how it works and Rangiku tells him to trust her, they are interrupted by an incensed Hitsugaya, who observes that this is where Rangiku hides her sake bottles and angrily screams her name when Rangiku frantically attempts to explain what is happening.

Some time later, the members of the Third Division kneel before a set of tables with sake and food set out within their barracks as Amagai and Kibune stare in confusion. Upon approaching Amagai from the side, Izuru explains that this is a welcome party for him and Kibune, which Amagai is both surprised and pleased by. Once Amagai and Kibune are seated, Izuru reveals that he was told this would help solidify their bond and offers to pour a cup for him, only for Amagai to hesitate, to Izuru's perplexment. After a moment of internal deliberation, Amagai accepts Izuru's offer, though he expresses alarm at how much sake there is as Izuru fills the cup.

However, when Izuru is assured by Amagai that he meant nothing by this and announces the start of the welcoming party, Kanō and the other Shinigami merely grumble and glare at him without drinking their sake, causing a distressed Izuru to mentally note that he has never been to a party so depressing and that Rangiku's suggestion is having the opposite effect of what he intended. With Amagai sweating while he stares at his cup, Izuru proclaims that Amagai will now perform a toast and encourages the latter to do so, which leads Amagai to nervously say that he will be counting on all of them and drink all of his sake in one motion.

Suddenly, upon being praised by Izuru as someone who can clearly drink well, Amagai sets down his cup and begins blushing before informing Izuru that this is not the case, to the latter's alarm. Amagai states that he feels so grateful for such a party being thrown for him, and as the other Shinigami drink their sake, a swaying and unstable Amagai gets to his feet and claims to feel good, only to fall backward and lose consciousness. Rushing to Amagai's side alongside a concerned Izuru, Kibune informs the latter that Amagai actually has zero tolerance for alcohol and can get drunk on pickles made from sake yeast, leaving Izuru incredulous.

When Izuru questions why Amagai did not refuse the sake, Kibune theorizes that he perceived the mood of those around him and felt that he should not refuse. While one of the Shinigami leaves to get a pail of water and a towel at Izuru's request, Aida approaches him alongside Inose and inquires about what they should do, but as Izuru observes that they cannot really continue the party with Amagai in this condition, Kibune suggests that they instead talk a bit more and get to know each other since the Shinigami set up this opportunity for him and Amagai since he would like to learn all of their names and faces as best he can.

Meanwhile, Shunsui lies on a rooftop in another part of the Seireitei, where he is approached by his lieutenant, Nanao Ise, and brings up the Third Division having a drinking party. With an unimpressed Nanao observing that they are doing so during the day and as a welcoming party for Amagai, Shunsui approves of this since sake tastes best during the day and lets one become heavily drunk prior to wondering if Amagai is a drinker and someone he can become friends with, both of which Nanao remains noncommittal on, to Shunsui's disappointment. Back at the Third Division barracks, an unconscious Amagai is tended to and kept stable with towels.

Nearby, Kibune speaks with an unseated Shinigami and writes down information in a book before politely thanking him and exiting, which leaves Inose and Aida to look back at Amagai and decide to simply ignore him since they have done fine with only Izuru until now and do not need a captain like this. Outside, Izuru leans against the wall and berates himself for having taken Rangiku's advice prior. Approaching Izuru from the adjoining walkway, Kibune comments on the strong solidarity of the Third Division and praises Izuru for keeping them together in the absence of a captain, though Izuru downplays this as being not so difficult.

The Third Division's Battle
Suddenly, through Jigokuchō, Rin Tsubokura alerts the Gotei 13 from the Shinigami Research and Development Institute that thirteen Menos Grande have appeared in area 35 of the Dangai and are presently headed toward Soul Society, leaving Chōjirō, Rangiku, and Hitsugaya shocked at their numbers while Yamamoto orders the Third Division to dispatch the Menos Grande immediately. With Amagai still unconscious, Kibune tells Izuru that they must go regardless because this cannot be helped and assures him that the Kōryū will be restrained for them, leading Izuru to declare that the Third Division will enter the Dangai.

At the grave of Kakyō, 7th Division Lieutenant Tetsuzaemon Iba stands with Komamura and observes that the Third Division is moving out, which prompts Komamura to muse that the Seireitei may be changing after all with a man who distinguished himself on an expedition being promoted to captaincy and upending precedent. When Iba inquires about the identity of the two captains who participated in Amagai's assessment, Komamura admits that he does not know and asserts that something new is happening regardless. Simultaneously, at the Central Senkaimon, Izuru tells the assembled Shinigami that they will split into groups of four to battle the enemy.

After warning the Third Division to be as cautious as possible since they are facing Menos Grande, Izuru has them enter the Central Senkaimon. Shortly afterward, Izuru and the other Shinigami run through the Dangai and see Menos Grande emerging from the walls in front of them. Having the other groups spread out, Izuru draws his Zanpakutō and releases his Shikai, Wabisuke, to rapidly cut through one of the Menos Grande, leaving it to disintegrate behind him. Another Shinigami evades a Cero fired by a second Menos Grande, which is quickly cut in several places by other Shinigami, destroying it.

With three more Menos Grande being destroyed by other members of the Third Division, Rin confirms that they have purified five in total and have eight more to go, only to be alarmed by an alarm on his monitor. Once the sixth Menos is dispatched, the Dangai begins shaking around the Shinigami and the walls begin flowing downward as Rin warns them that the Kōryū has returned, which he is bewildered by due to its supposed quarantine. Within the Dangai, Izuru and the other Shinigami see the Kōtotsu barreling toward them and impacting two of the remaining Menos Grande while Rin measures it as being 200 meters away from the Third Division.

When Kibune appears behind him with Shunpo, Izuru questions why this has happened, leading Kibune to admit that he does not know since his request to restrict the Kōryū was received. At Izuru's command, the Shinigami begin retreating through the Dangai, and when another Menos Grande fires a Cero at Inose, Kibune moves in front of him with Shunpo and blocks the Cero with his Zanpakutō prior to slashing through the Menos Grande's shoulder, causing it to begin dissipating as the Kōtotsu catches up to it, and moving back to Inose's side to assure the latter that he will guard the rear.

However, while the Shinigami continue to flee from the Kōtotsu and find themselves unable to outrun it, to Kibune's concern, Amagai tells them to move aside and leaps over the Shinigami to land before the approaching Kōtotsu, causing Kibune to smile as Izuru rushes toward Amagai's side. Telling Izuru to stay back, Amagai draws a tuning fork from his hip and levels it at the Kōtotsu, which prompts one of the Shinigami to demand to know if he is crazy. After Amagai reiterates that he will protect the Third Division so long as he is their captain, Kibune tells Izuru to closely observe Amagai's true power in this moment.

A yelling Amagai thrusts the tuning fork toward the Kōtotsu just as it collides with him, causing the latter to burst apart and disintegrate in an explosion of green energy, leaving the Third Division stunned as he cleans its tines with several pieces of cloth and turns around with a smile before approaching Kibune, whom he asks about his certainty of sending a request for the Kōryū to be restrained. Once Kibune affirms this, Amagai muses that the Shinigami Research and Development Institute would be unlikely to miss such a request, to the concern of those present, but dismisses this and asks if anyone is injured.

Aftermath
Following Inose denying this, Amagai turns to Izuru and praises his performance in the field as what he would expect from someone who filled in during a captain's absence. Though Izuru insists that it was nothing, Amagai expresses relief that they are all okay and instructs the Shinigami to head back with him while walking past them, causing Inose and Aida to admit that he is an extraordinary man. Suddenly, Amagai stops and falls on his back once more, and upon rushing to his side alongside the other Shinigami, Izuru realizes that he is still drunk and destroyed the Kōtotsu while inebriated. With Aida's help, Kibune lifts Amagai by his arms to carry him back and encourages Izuru to come with them, which the latter does with a smile.