The Rise & Fall of Masaki Kurosaki is an event taking place several years prior to Ichigo Kurosaki meeting Rukia Kuchiki. It involves 10th Division Captain Isshin Shiba going to the Human World to investigate a number of Shinigami disappearances, where he meets Masaki Kurosaki for the first time.
As Rangiku Matsumoto looks for her captain, two Shinigami nearby comment on how it must be hard for her. Borrowing a tray one of them is holding, Rangiku throws it into a nearby tree, eliciting a yell of pain. As Rangiku states it was a perfect hit, her captain reveals he stopped it before it hit his face. As she kicks it into his face, prompting him to say his sharp nose is broken, she tells him to get back to work, referring to him as Captain Shiba. Handing the tray back to the Shinigami, he states it cracked because of Rangiku, who claims it is his fault for neglecting his job. When Rangiku brings up his family, saying he will dishonor the household by acting this way, Isshin claims she is using his family as an excuse to slowly increase his workload. Grabbing her by the arm, he comments on the shininess of her breasts, prompting her to attack him. When they arrive at the 10th Division barracks, Tōshirō Hitsugaya hands them a stack of papers he has completed, prompting Isshin to, hoisting him in the air, proclaim he is worthy of becoming the next captain.
When Rangiku says she should be captain because of her rank, Isshin says if someone like her were to lead the division, it would crumble. As Hitsugaya states he is right, for his Bankai training is going well, Rangiku asks him why he is agreeing. As they argue, Isshin, telling Rangiku to not pester him too much, looks for his manju. As Hitsugaya tries to tell him he has something to report, Isshin asks him if he saw his manju. When Hitsugaya, admitting to having eaten it, informs him of two Shinigami dying in Narukishi last month, Isshin heads off to investigate by himself, leaving Rangiku Matsumoto and Hitsugaya to run the Division in his stead. When Rangiku tries to run after him, Hitsugaya tells her to let him go, as he is going alone because he knows it is dangerous. When Rangiku says she knows this, which is why they should go, Hitsugaya states with their current power level, they would only get in his way.
Elsewhere, in a laboratory, a figure asks if anything was obtained, prompting Gin Ichimaru to state they did not. Kaname Tōsen explains how even though they were able to equip Hollows with target Hollowfication, it is too virulent and does not work on regular souls or division members. Stating this is fine, the figure says they will be able to find the Visored and carry out Hollowfication experiments, therefore "killing two birds with one stone". Stepping into the light, the figure, revealing himself to be Sōsuke Aizen, tells Gin and Tōsen everything will go according to plan.
Meanwhile, two 10th Division officers, moving through Narukishi, comment on how it is a rainy night. When one of them reveals the two Shinigami who were stationed there before them died on a rainy night, Isshin, appearing behind them, says it is good to know rainy nights are dangerous. When the Shinigami ask him why he is there, he says he is looking for a toilet. When the Shinigami call him out on his boldfaced lie, he tells them to go home if it rains, as he wants to "pee alone". High above them, a shadowy figure stands behind the clouds.
At the Ishida residence, Masaki is asked by her aunt about the "holy training". When Masaki says she is doing the training "little by little", her aunt, yelling at her, asks if she understands her position, stating the Ishida family has accepted to train Masaki, the last of the Kurosaki family, as a Quincy. As Masaki comments on the meat being delicious, Ryūken Ishida, interrupting them, tells his mother to stop, as her voice can be heard from outside. As his mother, heading back to her room, says she will have his food prepared, Ryūken asks towards his father. Stating he is at Funfte Field, she says she would like to know when he will be back as well.
When Ryūken asks Masaki to forgive his mother for taking her anger out on her, Masaki, saying she is not angry, thanks him for the food and heads back to her room. As Kanae Katagiri prepares Ryūken's dinner, Ryūken, stating Masaki knows his mother allowed her into the Ishida family for the sole purpose of protecting its pure Quincy bloodline, says he is not sure if she wants to marry him. When Katagiri says Ryūken thinking marriage among Quincy should be based on love is kind, and this kindness will make Masaki happy, Ryūken, asking why she thinks he is kind, says he wants Masaki to be happy, because if they are not happy, they cannot look positively at the future of the Quincy.
Meanwhile, the 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 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 Aizen wonders why Isshin is in Narukishi, Tōsen reveals he did not report he was going there, and Gin 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, sensing a powerful Reiatsu drawing near, runs into the hallway only for Ryūken 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 Katagiri go, as Echt Quincy like themselves should not be drawn into fighting so often.
Noting he is falling behind, Isshin notes how even though his foe's appearance is that of 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, 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 states this is not how a Menos fights. 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 Aizen thanks Kisuke Urahara for leaving his Reiatsu-concealing cloak behind, 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.
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. 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. 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.
Isshin states White is still a formidable foe even while missing an arm. 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. 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 Hollowfy 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, 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.
Wondering if Isshin was able to return to Soul Society and if someone got angry at him, Masaki thinks to herself she should have asked his name. Thinking about how Quincy are still alive, Isshin, thinking to himself about how brave she is for saving a Shinigami and saying she is a Quincy, wonders if he could meet her again to properly thank her. At Masaki's school, her friends talk to her about Ryūken, saying living with him must be exciting. As Masaki says there is nothing between them, one of her friends says she is not his type anyway. As the group bickers, Masaki bumps into a figure, to whom she apologizes. As the group walks away, the figure turns around, revealing himself to be Kisuke Urahara, and narrows his eyes.
After Isshin leaves for the Human World once more without informing anyone, Rangiku, finding his note, expresses outrage at how he never learns, throwing the crumpled-up note against the wall. At the Ishida residence, Masaki announces her return. As Ryūken welcomes her, her aunt reveals she knows her fighting White and saving Isshin. When Masaki tries to deny this, her aunt says she has proof, causing Ryūken to realize Katagiri told her. As Masaki's aunt continues to berate her for breaking the rules of the Quincy, Ryūken, confronting Katagiri, asks why she told his mother, reiterating his statement of there being no issues. Saying there actually was an issue, Katagiri explains how Masaki received a wound from White's attack, and if she is not cured with the original Quincy procedure, the pure blood of the Ishida family might get spoiled. When Ryūken expresses disbelief at this reasoning, Katagiri reminds him of how he said his marriage with Masaki would be the future of the Quincy. As Ryūken rushes back and tries to convince his mother it was not Masaki's fault, Masaki says it is okay before collapsing.
Rushing to her side, Ryūken, asking her if she feels sick, sees a Hollow hole forming on her chest. As his mother asks what it is, Ryūken, picking up Masaki, asks where his father is. When his mother says she does not know and will try to get in touch with him, Ryūken runs off with Masaki, leaving his mother calling after him. Running across the sky, Ryūken, wondering what is happening to Masaki, expresses regret for not helping her in her fight against White. Appearing next to Ryūken, a large Hollow is cut in half by Isshin, who tells him not to thank him. As Ryūken recognizes him as the Shinigami whom Masaki saved, Isshin, noticing the hole in her chest, attempts to move to her. Telling him not to touch her, Ryūken reveals to him she is like this because she protected him. As Isshin asks if it is being caused by the wound created by White, Ryūken, telling him only a Hollow could make this wound, begins to threaten Isshin before Urahara, telling them to stop, reveals there are ways to save Masaki.
Falling down a hole, Masaki, stating she does not feel scared and knows someone is looking for her, sees a Hollow face preparing to devour her. Back in the real world, Urahara tells Isshin and Ryūken he has been resaerching Masaki's condition for 100 years. When Isshin, stating he is not the age he looks, asks who he is, Urahara, revealing his identity, states he was expelled from Soul Society. As Isshin recognizes him, Ryūken, stating he does not care who he is, asks if he can save Masaki. Saying he never said he could return her to her previous state, Urahara states she will never go back to how she was. Telling Ryūken to lay her down, Urahara, explaining Hollowfication, states though it was meant to strengthen the soul of a Shinigami, the technology they possessed was not enough to control it, and what is happening to Masaki is the result of using this technique on a Quincy, which was not planned. When Ryūken asks if this means they cannot save Masaki, Urahara says they cannot return her to her previous state, but they can save her life.
Explaining what happens to a soul which undergoes Hollowfication, Urahara states the boundary between the soul and the outside world is destroyed, which causes the soul to destroy itself. Referring to this event as "soul suicide", Urahara states his hundred years of research has produced a way to stop the soul suicide - inserting something opposite to Hollowfication into the soul, which stops the Hollowfication from disrupting the soul and restores balance. As Isshin says he does not get it, Urahara states because of this discovery, he was able to stop the soul suicide in all cases, but it only stopped the soul suicide, and in order to save Masaki's life, prevent the Hollowfication, and allow her to live as a normal Human, a much stronger power is needed, one which acts as an opposing power, continually blocking the Hollowfication, and stays near Masaki until she dies. When Ryūken, calling him a liar, says there must be another way, Urahara, saying he caught on fast, states he cannot choose.
Telling Isshin he is the only one who can choose, Urahara, revealing and explaining a special Gigai which will make Isshin a being halfway between a Shinigami and a Human, states the opposite of a Quincy is a Shinigami and the opposite of a Hollow is a Human, so if he uses this, he will become a being completely opposite to Masaki. As Urahara, stating this has too many demerits, lists what will happen to Isshin if he does this, which includes not going back to being a Shinigami again, Ryūken, thinking to himself this has too many demerits, thinks there is no way he will accept it, Urahara explains how he will tie Isshin to Masaki and the Hollow inside her with a Reishi string, which will prevent him from leaving the Gigai.
As Urahara begins to paraphrase his statement, Isshin says he will do it. As Urahara expresses disbelief, Isshin, saying his explanations are too long and they are wasting time, states he will gladly give up being a Shinigami. When Urahara asks if he has any regrets, Isshin, echoing Masaki's speech to Ryūken, states if he let the one who saved him die because of his regrets, he would be ashamed of himself tomorrow. As Urahara states he will start the operation, Masaki, continuing to fall into the Hollow's mouth, is caught by Isshin, who says he came to protect her.
Stating he will not let the Hollow lay a finger on Masaki, Isshin fires a Getsuga Tenshō at it, splitting it in half. Realizing what has happened, Masaki expresses excitement as Isshin tells her she should not act like this while naked. Back in the real world, Urahara tells Isshin he has successfully completed the bond. Elsewhere, Katagiri, confronting Ryūken, asks him if he left Masaki with the Shinigami. When he tells her to go home, asking her to tell his mother he cannot protect the Quincy, she states it breaks her heart to see him sad. As a tear rolls down Katagiri's cheek, Ryūken agrees to come back with her.
Later, Isshin settles down with Masaki, the latter becoming a university student, and opens up a small clinic, with Urahara helping out. Isshin tells Masaki he was exiled from Soul Society after making a blunder, but she does not believe him. On June 17th, 1994, Yhwach initiates Auswählen, which robs "impure" Quincy of their powers. When Masaki is attacked by Grand Fisher, she no longer has access to her Blut, allowing Grand Fisher to kill her. On the same day, Katagiri falls into a coma, and three months later, she dies.