Short Summary
With Orihime captured by Aizen's forces, Ichigo heads to Hueco Mundo to get her back followed by Chad, Ishida and later Rukia and Renji. Along the way they're joined by a childlike yet friendly Arrancar, Nel, and her little group as they invade Aizen's stronghold and contend against the Arrancars guarding it.Main Summary
Orihime has been captured by Ulquiorra and taken to Las Noches, Aizen's base of operations in Hueco Mundo. Ichigo rushes off to save her followed only by Ishida and Chad, as Yamamoto had ordered the Gotei 13 to not go after her. Upon arrival in Hueco Mundo, Ichigo and friends find themselves in a remote observation post, staffed by two incomplete Arrancar, Aisslinger and Demourra. The two don't provide much information when defeated before the building collapses on them, but Las Noches is so large that it can be clearly seen even from far away.
While walking through the vast deserts to reach Las Noches, the Orihime Rescue Squad find a strange group- Nel Tu, a little girl Arrancar, her two friends Pesche and Dodondochaka, and a large Hollow worm. Despite an early misunderstanding involving their game of 'Eternal Tag', Nel is quite friendly and they happily join Ichigo in their efforts. The next obstacle is a giant sand Hollow, defeated by the surprise appearance of more reinforcements- Renji and Rukia. Unfortunately, the giant hollow is Not Quite Dead and sucks them down into the Forest of Menos.
The Forest of Menos is exactly what the name suggests; it's a giant underground forest where Menos Grande hang out. There's Gillians everywhere, some distinctly unfriendly Adjuchas, and one shinigami by the name of Ashido Kano. Ashido was once a normal Shinigami before an accident killed all of his team and trapped him in Hueco Mundo, and he's lived on his own in the forest ever since, fending off the Menos who live there and getting himself some neat trophies from their masks. Ashido is able to lead them out of the forest, but a rockfall cuts of his own escape, and the team continues on without him.
After that misadventure, Ichigo and companions finally reach Las Noches and manage to enter. But when they do, they find themselves in a room with multiple passages and no indication which might lead to Orihime. Ichigo takes his turn with the Smart Ball and suggests that they stick together and explore one at a time, but Renji shuts him down by appealing to Honor Before Reason. So they split up, and immediately walk into fights with Arrancar. And not just any Arrancar, but the Privaron Espada, who were once ranked among the top ten of the Arrancar, but were demoted when more powerful ones showed up. Also, they think that if they beat any of Ichigo's group, Aizen might reinstate them. So yeah, nice going morons.
Ichigo (with Nel tagging along) fights Dordoni, the 103rd Arrancar, a Spanish oddball who can summon tornadoes with his Zanpakuto, Giralda (named after the bell tower of Seville Cathedral). While Dordoni might be bizarre and quite affable, he's still a formidable opponent who forces Ichigo to call on his Hollow mask to win. After being defeated by Ichigo, he holds off the Exequias (translates to 'funeral rites' and is a group of Arrancar tasked with eliminating enemies who make it into Las Noches and executing Arrancar who fail) so that Ichigo can escape, dying in the process.
Ishida fights Cirruci, the 105th Arrancar, with Pesche's dubious help. She's a purple-haired lady who fights with her yoyo-like Zanpakuto, Golondrina (swallow, as in the bird). While Cirruci is able to keep him on the defensive for a while, Ishida ultimately ends the fight using seele schneider, a Quincy spell that is basically a lightsaber/super arrow that steals reishi from the environment. While this does not kill her, the Exequias do.
Chad gets thrown a bone in his fight with the 107th Arrancar, Gantenbainne, who uses the zanpakuto Dragra. Chad evolves his right arm's defensive power and awakens his left arm's offensive power, managing to win the fight on his own. Unfortunately, the awesome moment is not to last, as Chad then encounters Nnoitra, the current 5th Espada, who unceremoniously one-shots him. And somehow, Rukia and Renji have even worse luck with their encounters, as both of them encounter current Espada.
Rukia finds a strange masked figure who at first appears to be Kaien Shiba, Ichigo's doppelganger and the person Rukia failed to save prior to the series' beginning. But when "Kaien" starts encouraging her to turn on Ichigo, Rukia finds out the truth- the person is Aaroniero Arruruerie, the Noveno Espada. He ate the hollow who ate Kaien Shiba, which allowed him to take Kaien's appearance and powers for his own (supposedly this includes the powers from every hollow he's eaten, but he never shows any others). Aaroniero manages to impale Rukia and break Sode no Shirayuki, but Rukia is able to reform her blade right through what passes for Aaroniero's head, killing him.
Renji, on the other hand, doesn't do so well. His opponent is Szayelapporro Granz, brother of Yylfordt Granz, who he fought back in the living world. And as Szayel is something of an Arrancar Mayuri, he bugged his brother with recording devices and now knows how to counter Renji's moves. Uryu comes in to help, but Szayel prepared for him too by getting info from his earlier battle with Cirruci. Together, they still manage to lure Szayel into a trap, but the only thing it ultimately accomplishes is damaging his clothes (and causing him to temporarily leave the fight to change).
Ichigo, meanwhile, has also managed to find himself an Espada who completely outclasses him- Ulquiorra, the Cuatro Espada. He gets beaten up quite badly before Ulquiorra leaves and Grimmjow drags Orihime to heal Ichigo so they can finally finish that fight from the Arrancar Invasion arc. Ichigo manages to win with his greater mastery of his Hollow powers, but before he can actually do anything, Nnoitra attacks the exhausted Grimmjow and Ichigo. Ichigo is too exhausted to fight back effectively and Orihime is captured by Tesra (who keeps her in line by threatening to destroy her hairpins if she helps Ichigo), but the day is saved by none other than Nel Tu.
See, Nel Tu isn't exactly what she seems. Her full name is Nelliel Tu Odelschwank, and she was once the Tres Espada. At that time, Nnoitra was the 8th Espada, and had a serious one-sided rivalry with her. Furious that Nel hated fighting and would never rise to his provocations, he resorted to underhanded tactics. First, he ripped off the masks of her two fraccion, Pesche and Dodondochaka (who were more human-looking then), and when they fought, he used an illusion device created by Szayel to get in a solid strike to her back. This attack broke her mask remains, which caused her reiatsu to become unstable and her to turn into a child with no memory of her former self. Pesche and Dodondochaka knew all along that she was once an Espada, but never said anything because this way, Nelliel could live the carefree life she desired most. But now that Ichigo's life is on the line, Nel regains her adult form and power and stomps Nnoitra.
Unfortunately, Nelliel is unable to land the final blow as her unstable reiatsu causes her to revert to child form. At this point, our heroes are in tough straights- Nnoitra and Tesra are torturing Ichigo, the Septima Espada Zommari has found Rukia's unconscious and seriously wounded body, and Szayel has returned to torment Renji and Uryu with his Resurrecion. At this point, yet another set of Big Damn Heroes arrives- reinforcements from Soul Society, led by Byakuya, Kenpachi, Mayuri, and Unohana. While Unohana tends to the wounded, the other captains face off against the Espada giving the original rescuers trouble.
Byakuya fights Zommari, who has the power to take control of things with his eyes (and his Resurrecion has a lot of eyes to work with). Unfortunately for him, Byakuya's bankai has too many separate components for him to control at once, and he admitted to trying to kill Byakuya's sister, so he dies quickly. Mayuri fights Szayelapporro in a battle of who's the more Crazy-Prepared Mad Scientist, and wins when Szayel tries to use Nemu to grow a new body after his orignal one is destroyed by Mayuri's bankai. This was a terrible idea, because this meant that he absorbed a drug that was in Nemu's body which caused And I Must Scream and destroyed his ability to fight back against Mayuri. Nnoitra is able to give Kenpachi trouble to the point where he is forced to start fighting back with kendo, but doesn't last long after that.
The battle is over, Orihime is saved... but now comes the fun part. Coyote Starrk yoinks Orihime back to Aizen, and Aizen reveals that Orihime wasn't kidnapped because of something Aizen wanted from her specifically. She was bait, because Aizen knew that Ichigo would come running after her because she's his friend, and Soul Society would probably send Captains after her because of her powers. Now that Ichigo and four captains are in Hueco Mundo, Aizen traps them there for the time being and prepares to attack Karakura Town.
Which is actually a fake Karakura Town created by Urahara and Mayuri with no inhabitants except the rest of Gotei 13's main characters, but Aizen is fine with fighting a massive battle there.
Hueco Mundo Arc has the following tropes
- Affably Evil: Several Arrancar on Aizen's side are still rather friendly. Coyote Starrk, for example, apologizes before kidnapping Orihime back.
- Adaptation Expansion: The Forest of Menos section, which was actually meant to be drawn in the manga. But time constrictions forced Kubo to move the story along. So it was handed to the anime staff instead.
- Big Damn Heroes: Several levels. First, there's Rukia and Renji in Hueco Mundo, then Nel for Ichigo, and finally the Captains showing up.
- Conservation of Ninjutsu: Aizen plans to divert some of the Captains to Hueco Mundo because he knows that they're basically Soul Society's entire military force, with the rank and file meaning precisely squat to his arrancar.
- Gambit Pileup: Orihime's kidnapping was actually an attempt to divert a large portion of the Gotei 13's fighting force into Hueco Mundo while he attacked Karakura Town, but it turns out Yamamoto expected that. And then it turns out that Aizen expected that, or at least is fine with the results.
- Hoist by His Own Petard: If Szayel hadn't used his Gabriel ability on Nemu, he wouldn't have absorbed the drug there and wouldn't have died in a horrible And I Must Scream.
- Let's Split Up, Gang!: Once inside Aizen's fortress, Ichigo's group split up to cover more ground to find Orihime. It turns out to be a big mistake.
- Mirror Match: The captains who come to rescue Ichigo and friends face off against the Espada who are the closest match for them- Nnoitra to Kenpachi, Szayel to Mayuri, and Zommari to Byakuya.
- Rescue Arc: The second rescue arc of the series with Ichigo and his friends trying to rescue Orihime from Aizen after he had her kidnapped to use her powers.
- Storming the Castle: The majority of the arc is spent raiding Aizen's fortress to get Orihime back.
