As two Shinigami, noting it has begun to rain, discuss going back to Soul Society, one of them saying they can stay hidden for now because Isshin Shiba will do something about this. Thinking Shinigami are being targeted because of their Reiatsu, Isshin, deciding to draw it out, exerts a large amount of Reiatsu. As the two Shinigami comment on his Reiatsu, one of them is killed by an unseen assailant. Hearing screams, Isshin, realizing it did not react to his Reiatsu, stops in his tracks when something lands behind him. Upon seeing the eerie figure, Isshin wonders what it is.
As the Hollow creature turns and roars at him, Isshin, noting its unusual black color and closed Hollow hole, states its Reiatsu is still a Hollow's. As the Hollow creature charges at him, Isshin unsheathes his Zanpakutō. Back at the laboratory, as Sōsuke Aizen wonders why Isshin is in Narukishi, Kaname Tōsen reveals he did not report he was going there, and Gin Ichimaru states this will cause trouble. Referring to Isshin's arrival as an "unexpected harvest", Aizen asks to see the fight up close.
At the Ishida residence, Masaki Kurosaki, sensing a powerful Reiatsu drawing near, runs into the hallway only for Ryūken Ishida to ask her where she is going. Telling her Quincy only fight Hollows after the Shinigami doing so die, he says even in this case, they should let gemischt like Kanae Katagiri go, for echt Quincy like themselves should not be drawn into fighting so often.
Using Hohō to stop himself in midair, Isshin notes he is falling behind. Blocking a strike from the Hollow creature, he notes how even though his foe looks like a Hollow, it feels like he is fighting a Shinigami. As he thinks to himself this is a hard struggle, a member of the 13th Division, calling out to him, tells him Karakura Town is under the jurisdiction of the 13th Division. As Isshin realizes he has passed the jurisdiction boundary, the Hollow creature, moving away from him, charges at the other Shinigami. As Isshin yells at him to run, the Hollow creature obliterates the Shinigami with a Cero charged between its horns.
As both Masaki and Ryūken notice the explosion, Masaki begins to run again. When Ryūken tells her to wait, Masaki explains to him how even though she admires how he takes everything and everyone into consideration before acting, if she were unable to save someone because of a custom, she would not be able to live with herself. As she runs off, Ryūken tells Katagiri to prepare the "Reishi armor".
Startled by the power of the Cero, Isshin, stating this is not how a Menos fights, clashes with the creature. Stating it is impossible for a creature like this to exist without Soul Society knowing, Isshin asks who is protecting it. When he does not receive an answer, Isshin, stating he will attack him regardless of whether he answers or not, releases his Zanpakutō, Engetsu. As he prepares to attack the Hollow creature, Isshin is attacked from behind by Aizen. As Isshin falls, Aizen, commenting on the cloak he is wearing, reveals it can shield the wearer from view if infused with Kidō. As he thanks Kisuke Urahara for leaving such a "wonderful parting gift", Isshin, getting up, realizes the slash was not from the Hollow, but from a Zanpakutō. As Isshin, knowing a traitor must be hiding, calls out to them to reveal themselves, Gin states he must have realized he was not hit by the Hollow. When Aizen states he is leaving, Gin asks if this is okay.
Aizen says Isshin will not be able to use his Bankai with the wound he has just received, and if the "sample" can be defeated by a captain-level Shinigami using only Shikai, it was a failure in the first place. Telling Aizen to call it "White", Tōsen states it is completely different from all the types of Hollow they have created thus far, as it is based on the soul of a Shinigami. Apologizing, Aizen states calling it "White" because of his inner "whiteness", even though it is clad in black armor, is something he finds ironic.
As Isshin clashes with White once more, the wound on his back spurts blood. When White tries to attack him from the side, Isshin steps on the blade, forcing White to the ground. As Isshin thinks to himself how he cannot fix his Reiatsu because of his wound, and how he will not be able to use his Bankai if this persists, White, roaring, slashes at Isshin, knocking him backwards, and lunges after him. Telling White not to underestimate him, Isshin generates a huge, flame-like wave of Reiatsu along his blade. As he and White clash, resulting in a large explosion, Masaki, watching from the ground, is almost hit by one of White's severed blade-arms.
After clashing with White once more, Isshin states he is still a formidable foe even while missing an arm. Charging at him again, White slashes at Isshin, who, blocking the blow, struggles to hold him off. Charging another Cero between his horns, White dodges a Heilig Pfeil. Turning to look at the attacker, Isshin sees Masaki with her Spirit Weapon, a bow, which has another arrow prepared. As Tōsen says he will kill her, Aizen, stopping him, says to wait and watch what happens. As White launches himself towards Masaki, Isshin, trying to stop him, is halted by his wound. Trying to shoot White with more Heilig Pfeil, Masaki, realizing she cannot hit him while he is moving, allows herself to get attacked. Saying she has him, Masaki shoots White through the head.
As White's body falls to the ground, a huge pustule swells out of it. As Isshin pulls the body away, an enormous explosion engulfs the surrounding area, prompting Tōsen to state how it blowing up was not foreseen. Seeing Isshin lying on the ground, Masaki, rushing over to him, asks if he is okay. When Isshin comments on how shameful it is for a captain to be saved by a girl, Masaki states he would not be so wounded if he had not protected her, prompting him to state they are even because of this. When Masaki tells him not to move because she will heal him, Isshin, wondering how she could have defeated White by herself, asks who she is. Wondering what Isshin, a Shinigami, would do if he knew she is a Quincy, Masaki reveals her name and species. Surprised by this, Isshin, laughing, says it is the first time he has actually met a Quincy, stating it is strange to actually meet a real one. As Masaki wonders if all Shinigami are like this, Ryūken, standing above them, decides to leave, as Masaki is all right, and Katagiri, standing next to him, complies.
Back at the laboratory, Tōsen, saying White had reached the final stage of the "transformation", says it was a failure, stating though they created it to Hollowify Shinigami, it was a "fiasco". Stepping in from behind, Aizen, stating this is not true, explains how White straying away from the original goal meant it was surpassing it, saying they could not predict this, which is "interesting". Stating a Hollow created from a Shinigami chose a Quincy, a being opposite in many ways to it, Aizen asks if they do not want to see what comes after this.
As Isshin finishes up his report, Captain-Commander Genryūsai Shigekuni Yamamoto, stepping forward, says even though he went without permission, his actions kept the deaths and damage to a minimum, so he will overlook his violation of the rules this time. As Isshin thanks him, Mayuri Kurotsuchi comments on how it is a shame to not have succeeded in recovering the body of the "mysterious Hollow". As Isshin begins to leave, Yamamoto asks him if he does not think there is anything else worth mentioning. Recalling Masaki, Isshin says there is nothing else.