Rukia Kuchiki & Ichigo Kurosaki vs. Fishbone D

 is a battle that initially takes place between the Shinigami Rukia Kuchiki and the Hollow Fishbone D, only to be concluded by Ichigo Kurosaki after gaining Rukia's Shinigami powers.

Prelude
As Ichigo Kurosaki enters his room after a fight with his father, he sees a Jigokuchō fly in front of him, which he mistakes for an ordinary butterfly, before watching in shock as Rukia Kuchiki steps into his room on top of his desk. Rukia descends to the floor and notes that "it" is close, only to be interrupted when Ichigo angrily kicks her in the back while demanding to know what she is talking about. As she lies on the floor, a stunned Rukia asks Ichigo if he can see her and notes that he just kicked her.

Wondering what Rukia is talking about, Ichigo confirms that he can see her before suddenly being kicked in the face by Isshin, who berates him for making so much noise. Returning the blow while asking how he can be quiet while subduing intruders, Ichigo points to Rukia and demands to know where their home security is, only for a confused Isshin to ask what he is talking about. While Ichigo continues to motion to her, Rukia reveals that she is a Shinigami that cannot be seen by ordinary people. Elsewhere, Fishbone D chases down the Dead Girl and devours her before noticing a strong spiritual presence nearby.

Back at the Kurosaki Clinic, Ichigo recounts Rukia's explanation that she is a Shinigami sent from Soul Society to exorcise demons and claims to believe this before flipping a table and demanding to know how he could ever believe such a thing. Watching this, a surprised Rukia asks if he really does not believe in Shinigami despite being able to see ghosts, which Ichigo confirms before elaborating that he has never seen a Shinigami before and does not believe in what he cannot see. After admitting that Rukia is clearly not Human, Ichigo tells her to stop playing Shinigami and calling her a "pipsqueak" as he grabs her head. Angered by this, Rukia uses '''Bakudō #1. Sai''', binding Ichigo's arms.

As he falls forward in surprise, Ichigo demands to know what Rukia did to him. Taunting Ichigo over his inability to move, Rukia explains that this is Kidō, a high-level spell that only Shinigami can use, and reveals that she has lived ten times longer than Ichigo despite her appearance before claiming that not being permitted to execute anyone not named in her orders is the only thing preventing her from killing Ichigo on the spot for his insolence, which he should be grateful for. As an angered Ichigo curses her and her attitude, he is shocked when Rukia pulls out her Zanpakutō and brings it down, only to see her press the end of its hilt against the forehead of the glasses-wearing ghost that had been hanging around him.

The ghost begs her to not send him to Hell, but Rukia assures him that he is instead going to Soul Society and that it is a restful place. As Rukia removes the hilt from his forehead, leaving a shining emblem on it, the ghost sinks into the floor in a pool of blue light. While the light fades and a Jigokuchō flies away, a confused Ichigo asks Rukia what happened to the ghost, prompting her to reiterate that she sent him to Soul Society, which is referred to as "passing over" in the Human World, and decides to explain it to him so that he fully understands.

Pulling out a sketchbook and marker, Rukia explains that there are two types of spirits in the world: Pluses, the normal spirits that Ichigo normally sees, and Hollows, evil spirits that attack both the living and the dead to devour their souls, both of which she illustrates. When Rukia asks him if he has any questions so far, Ichigo sarcastically wonders why her drawings are so bad, prompting Rukia to draw a mustache on his face with her marker, to his horror, before continuing. Rukia details how Shinigami have two jobs: the first is to send Pluses to Soul Society with Konsō as she just did, while the second is to purify Hollows, which is what she is here to do right now.

When Rukia confirms that there is a Hollow wandering around, Ichigo tells her to hurry up and get rid of it, only for Rukia to admit that she has not been able to sense it recently and theorizes that there is a powerful force obstructing her senses. However, having heard Fishbone D roar, Ichigo demands to know if she cannot hear the bloodcurdling howl and if this is not the Hollow she is after, prompting a confused Rukia to state that she does not know what Ichigo is talking about before stopping in shock as she suddenly hears Fishbone D's roar as well, which she identifies as definitely belonging to a Hollow.

Upon hearing a crash below and Yuzu Kurosaki screaming, Rukia runs to the door and opens it, only to stop in shock as she suddenly feels Fishbone D's powerful Reiatsu. As Rukia wonders how she could not have sensed this Reiatsu before, an injured Karin Kurosaki calls out to Ichigo and stumbles through the hall before falling in front of Ichigo's door. Reaching out to Ichigo, Karin reveals something attacked Yuzu and their father and tells Ichigo to run as she collapses. While kneeling down to check on Karin, Rukia confirms to Ichigo that she is alright and merely passed out, only to stop upon seeing Ichigo straining against his bonds.

Battle
Despite Rukia's warning, a yelling Ichigo manages to shatter the spell restraining him. With Rukia left shocked by a Human like Ichigo breaking through a spell with his own power, Ichigo grabs a baseball bat and runs downstairs, where he finds his injured father lying in the damaged living room before seeing Fishbone D. As a frightened Ichigo admits that he thought it would look like a normal Human and attempts to calm himself down, he sees Yuzu in Fishbone D's hand, prompting him to run toward the Hollow while screaming in rage. However, Fishbone D merely punches Ichigo away, shattering his baseball bat in the process, before attacking him once more.

Suddenly, Rukia appears and cuts into Fishbone D's arm, causing it to scream in pain as it drops Yuzu, whom Ichigo catches. As Ichigo calls out to Yuzu and asks her if she is okay, Rukia tells him to compose himself because Fishbone D has not yet devoured his sisters' souls, to his surprise. When Rukia notes that even his father has not yet had his soul devoured, Ichigo wonders why Fishbone D attacked his family if not to devour their souls, prompting Rukia to elaborate that Hollows are drawn to high levels of Reiryoku and attack opportunistically before bringing up Ichigo's feats of spiritual power as evidence that Fishbone D is actually after him.

A stunned Ichigo asks if it is his fault that his family is lying on the ground bleeding, which Rukia tries to dissuade him from thinking, only to be punched away by Fishbone D from behind. As she crashes into a wall, Rukia chastises herself for not guarding her flank, only to be shocked upon seeing Ichigo standing in front of Fishbone D, whom he asks if he is after Ichigo's power before demanding that the Hollow fight him one-on-one. A roaring Fishbone D extends his neck to devour Ichigo, only for Rukia to intercept the attack with her body, damaging Fishbone D's mouth in the process. As Fishbone D rears back in pain, Rukia falls to her knees while blood trails behind her.

Berating a shocked Ichigo for not realizing he would be no match for Fishbone D, Rukia asks if he thought everything would be over if he gave the Hollow his soul before stating that they will all become food for him at this point. As Fishbone D recovers and narrows his eyes, Rukia pulls herself to a nearby pole and asks Ichigo if he wants to save his family, which Ichigo immediately confirms before asking if there is a way to do so. Affirming this, Rukia leans against the pole and points her Zanpakutō at Ichigo before declaring that he must become a Shinigami himself, to Ichigo's surprise. Rukia details how Ichigo must run her Zanpakutō through his body so she can give him her powers.

While Fishbone D continues to roar, Rukia admits that she does not know if this will work before asserting that there is nothing else they can do. As Fishbone D begins to walk toward them, Ichigo tells Rukia to give him her Zanpakutō and addresses her as a Shinigami, prompting Rukia to tell him her name. With Fishbone D charging toward them, Ichigo grabs Rukia's Zanpakutō by the blade and introduces himself in turn before pulling the blade into himself as Rukia pushes, resulting in a powerful surge of energy that releases waves of force in all directions. Pushing through the force, Fishbone D suddenly has his left arm cut off by Ichigo.

With Ichigo having successfully gained Shinigami powers and a large Zanpakutō of his own, a stunned Rukia, now clad in a white shihakushō, notes that Ichigo took all of her power despite her only meaning to give him half and wonders who he is as Ichigo charges at Fishbone D. While Rukia states with disbelief that she has never met a Human with enough Reiryoku to confuse her senses, enough strength to break through a binding spell, and enough power to make a Zanpakutō as large as their own body, Ichigo cuts off Fishbone D's right leg and declares that he will pay for hurting his family before slashing through the Hollow's mask, causing Fishbone D to disintegrate and disappear.

Aftermath
While Ichigo falls unconscious, Kisuke Urahara, in search of a place to safely conceal the Hōgyoku, approaches Rukia and offers her a special Gigai, which begins to slowly drain her spiritual powers with the ultimate goal of turning her into an ordinary Human with no powers at all. The following day, Ichigo wakes up in his bed and discovers he and his family are uninjured, while the damage to the Kurosaki Clinic is claimed by his father and sisters to be the result of a truck crashing through the wall. Believing Rukia went back to Soul Society, Ichigo is shocked when she appears at his school in the guise of a student and tells him that he must take up her Shinigami duties.