Leaving Hueco Mundo for the Human World, Sōsuke Aizen leaves control of Las Noches to Ulquiorra, who returns from the other dimension by ripping an opening back into Hueco Mundo. Awaiting Ichigo's arrival, he asks Orihime Inoue if she feels any fear, because Aizen does not need her anymore, there is no one left to protect her, and she will die in Hueco Mundo all alone. Boldly answering no, she states she has confidence in her friends and Ichigo, and she is not fearful because her heart is with them. She explains how she left to protect them, and at first did not understand why they followed her when she was trying to protect them, but she eventually understood their actions. Unable to understand how she can harbor such feelings, Ulquiorra, pressing her further, asks her what a heart is, as he hears Humans talk of it all the time as if it is was a physical concept; reaching out to touch the area above her heart, he asks where he can find it. Just as he is about to further interrogate her, Ichigo breaks in, prepared to fight. Ulquiorra unsheathes his sword to kill Ichigo in order to protect Las Noches.
When Ichigo tells him to get away from Orihime, Ulquiorra states he has every intention of doing so: since Aizen's orders are to guard Las Noches in his absence, he has no orders to kill her. He states unlike her, Ichigo is different, as killing him would be protecting Las Noches. When he resolves to destroy him with his sword, Ichigo, surprised, states he believed he would have to force him to take out his sword, asking Ulquiorra if he finds him a worthy opponent. The Espada states that at the very least, he sees him as someone who must be destroyed.
The two battle, with Ichigo on the defensive blocking Ulquiorra's amazingly fast attacks. Deciding to go on the offensive, he follows the Espada's movements close enough to catch his arm and land a blow. Though the blow does not injure him, it proves Ichigo is now stronger, able to see his movements, which he could not do so last time they fought. Undeterred, Ulquiorra shows his true speed to Ichigo, who is amazed he can move even faster. Closing in on Ichigo, he is repelled by Orihime's Santen Kesshun.
When Ulquiorra asks her what she is doing and why she helped Ichigo, Orihime does not know what to say. Before Ulquiorra can tell her why she interfered, Ichigo, interrupting, says none of it matters. When he fires a Getsuga Tenshō, Ulquiorra tells him by now he should know by now this technique does not work on him. Ulquiorra is surprised when Ichigo does not release the blast, but keeps it in his sword so his blows have the power of Getsuga Tenshō behind them. Before Ichigo can gain any footing, Ulquiorra, deflecting the attack, states though Ichigo may think he has developed a skill to use against him, he must have forgotten the technique will not work against him even with his mask on, and without his mask, he has no hope, as it does not matter how he uses it. When Ichigo tries to attack Loly Aivirrne and Menoly Mallia, who grab Orihime while she stands back from the fight and threaten to pluck out her left eye if he advances on them, Ulquiorra, intercepting Ichigo, redirects his Getsuga Tenshō. Telling Loly not to get the wrong idea about his actions and he is not helping her, he continues blocking Ichigo's way to Orihime while monitoring the situation behind him. As he tells Ichigo he will have to kill him in order to fight anyone else, they are interrupted by the arrival of Yammy as he bursts through the floor.
When Yammy states he is there to help him, Ulquiorra, stating he did not ask for his help, he notices Yammy has fully recovered. Telling him his job is elsewhere, Ulquiorra suggests he go back to sleep or fight the other Captains who are nearby, which Yammy refuses to do. When asked by Yammy about why the female Arrancar are there, Ulquiorra, telling him to ask them, turns around to engage Ichigo once more and block his path to Orihime. Defeating Menoly and Loly, Yammy asks Ulquiorra if he is allowed to kill Orihime next, but Uryū, arriving, uses a special landmine developed by Captain Mayuri Kurotsuchi to critically injure Yammy, causing him to fall to the bottom of Las Noches.
Donning his Hollow mask, Ichigo proves to be completely resistant to Ulquiorra's attacks, even beginning to crack his blade. As Ichigo fires another Getsuga Tenshō, Ulquiorra, dodging it, moves through the hole in the wall to the outside. Firing a Cero at Ichigo, he is surprised to see Ichigo effortlessly block it. Using Sonído to get above Ichigo, Ulquiorra heads to the top of the dome of Las Noches, with Ichigo close behind. As Ichigo notes their location, Ulquiorra reveals to him there are two things forbidden within Las Noches: the first is using the Espada's Gran Rey Cero, and the second is any of the Espada of rank four or above releasing their Zanpakutō, as either has the potential power to destroy the fortress. Releasing his own Zanpakutō, Murciélago, Ulquiorra warns Ichigo to stay focused and alert before using Sonído and attacking him with Luz de la Luna. Though Ichigo defends himself with a Getsuga Tenshō reflexively, the upper-right portion of his mask is destroyed. Noticing the reflex, Ulquiorra says if Ichigo had not done so, his head would be lying at his feet.
Stating Ichigo's power has grown, Ulquiorra notes how he can use his mask longer, but he still easily shattered it. He attacks Ichigo with Luz de la Luna. The javelin hurtles toward Ichigo, who dodges until Ulquiorra, getting in close, goads him into using Getsuga Tenshō. He states since Ichigo is at his strongest and Getsuga Tenshō is his strongest attack, he should use it. When Ulquiorra promises to show him how strong he really is, Ichigo, stating he was going to do so anyhow, releases the attack, but Ulquiorra is completely unharmed. He states Ichigo's Getsuga Tenshō is similar to his Cero. When Ichigo disagrees, Ulquiorra, noting he has not seen it yet, demonstrates the Espada's fully powered Cero Oscuras.
Critically injuring Ichigo, the Cero Oscuras completely destroys his mask. As Ichigo falls, Ulquiorra, throwing him into a nearby building, tries to force Ichigo to give up, believing he has successfully proven himself to be vastly stronger and Hollows are superior to Humans and Shinigami in power. When Ichigo tries to use Getsuga Tenshō in defiance, Ulquiorra, losing his calm, slices him with his javelin, destroying the tower they are in, and says it is useless for Ichigo to keep trying. Striking a falling Ichigo again, sending him flying into another pillar, he, picking Ichigo up by the throat, tells him to just drop his sword and give up, as he can see the difference in their strength. Asking Ulquiorra if he thinks he should give up just because he is stronger than him, Ichigo states he has always known Ulquiorra was stronger, but nothing he has seen has changed his mind, and he will defeat him regardless. Hearing this, Ulquiorra, deciding to show Ichigo true despair, enters his second release form.
Ulquiorra reveals to the stunned Ichigo only he among the Espada has a second release form, Resurrección: Segunda Etapa, which even Aizen has not witnessed. When Ichigo, attempting to fight, shows no fear, Ulquiorra, noticing Ichigo intends to try and win this fight, resolves to rip Ichigo's body to shreds and make him understand fear. Flying at Ichigo in full force, he easily overwhelms him with his speed. Sending him flying into another large pillar, Ulquiorra, grabbing Ichigo's blade, hits him with his whip-like tail, sending him hurtling. When Ichigo, going on the defense, summons his Hollow mask, Ulquiorra expresses his inability to understand Ichigo's resolve, believing it is a Human's "heart", which causes them pain and will result in their deaths. Ulquiorra grabs Ichigo's face, breaking his mask in the process, and throws him into a nearby pillar. When Ichigo explains he has no choice, but to win the fight, Ulquiorra, calling him a fool, moves in on him once again. Arriving at the top of the dome, Uryū and Orihime finding Ulquiorra on top of a pillar, holding a defeated Ichigo up with his tail. Complimenting Orihime on her timing, he states the man in whom she has put all her trust is about to die. Charging his Cero Oscuras, Ulquiorra, ignoring Orihime's pleas to stop, sends it through Ichigo's chest,.
When Ulquiorra drops Ichigo's limp body, Orihime attempts to heal him. Blocking her path, Ulquiorra states her powers are not enough to bring Ichigo back to life. When Uryū fires a Heilig Pfeil at him, Ulquiorra easily deflects it with his wing. When even a volley of arrows proves ineffective, Ulquiorra states he believed Uryū to be the calmest of Ichigo's friends. Uryū states he is calm, which is why he is able to fight him. As Orihime's attempt to heal Ichigo fails, Ulquiorra severs Uryū's left hand. Despite this, Uryū tries to fight the Espada, but is quickly defeated. Not knowing what to do, Orihime, beginning to panic, screams for Ichigo to help. As Ichigo's arm begins to move, his hair begins to grow longer.
Ichigo stands, appearing entirely different, wearing a new Hollow mask with long horns. Shocked at his enemy's unexpected revival and believing Ichigo to be dead, Ulquiorra demands to know who he is. Summoning his sword to his hand without touching it, Ichigo answers with a roar. Believing words to be useless, Ulquiorra fires a Cero Oscuras. To his surprise, Ichigo fires a Cero powerful enough to counter it. As Ulquiorra refuses to believe a Human could release a Cero, especially one capable of blowing away his own, Ichigo, appearing behind him, effortlessly tears off the Espada's left arm. Quickly regenerating the arm, he states he is the only Arrancar capable of instantly regenerating any non-vital body part, as all others would rather have greater strength. Using Lanza del Relámpago, Ulquiorra tells Ichigo to stay right where he is because he does not want to risk using it at close range. The attack misses, creating a massive explosion in the desert, prompting Ulquiorra to state to himself it is a difficult technique to control. As a second spear is prepared, Ichigo appears right beside him, startling Ulquiorra because he used Sonído instead of Shunpo. Ichigo throws the detached arm at him, but Ulquiorra, slashing it away, thrusts the spear. Catching it with a single hand, Ichigo breaks it. When Ulquiorra is left dumbfounded, Ichigo, slicing him down the torso, slams him to the ground. As Ulquiorra states he cannot believe he was defeated by a Human turned Hollow, Ichigo, stepping on Ulquiorra's head, begins charging a Cero. Ulquiorra comments on how Ichigo shows no mercy, something very Hollow-like, but because Ichigo has beaten him, he has no reason to live. Ichigo releases the Cero, creating a vast and powerful explosion on the dome of Las Noches.
Ulquiorra barely survives, but his left arm, both legs, and lower torso are blown away in the blast. Tossing his tattered body aside, Ichigo prepares to impale his throat with his sword. Stopping him, Uryū states Ichigo will no longer be Human if he goes through with such a merciless finish. Ichigo stabs Uryū in retaliation, revealing while he can no longer tell friend from foe, his only intention is to protect Orihime. Just as he is about to attack Uryū with a Cero, Ulquiorra, having partially regenerated, ambushes him and severs one of Ichigo's horns, causing his Cero to disperse skyward.
The explosion shatters Ichigo's mask, and he collapses to the ground. As his body and leg begins to regenerate, Ulquiorra thinks to himself that it is merely a front as his internal organs, which were destroyed by Ichigo's Cero, cannot be regenerated. Even so, he believes Ichigo is finally dead. Suddenly, the hole in his chest completely repairs itself, and Ichigo awakes, shocking everyone with his ability to use High-Speed Regeneration. Removing Tensa Zangetsu from Uryū's chest, Ulquiorra throws it to the newly-awoken Ichigo, and demands him to take it and finish the fight.
Ichigo refuses, stating his arm and leg should be cut off too for the fight to be fair, as it was his inner Hollow who interfered. As Ulquiorra prepares to cut off his arm and leg, his body begins to dissolve into ash, and he realizes he is finished. He tells Ichigo to kill him now, but Ichigo again refuses. Woefully exclaiming Ichigo never does what he wants, Ulquiorra admits his interest in Humans has increased. Taking one final glance at Orihime, he asks her if she is afraid of him. With a saddened expression, she tells him she is not. In his final thoughts, Ulquiorra ponders what a heart is. He reaches out to Orihime with his hand, but before Orihime can grab hold of it, his hand begins to dissolve into ash. From her gesture, he, finally realizing what a heart is, believes there in his disintegrated hand is a heart. Ulquiorra fades entirely into the wind.