The Invasion of Soul Society is a major conflict detailing Sōsuke Aizen's and Gin Ichimaru's attack on the real Karakura Town located in Soul Society, and the final battle between Ichigo Kurosaki and Aizen.
Having defeated their challengers in the Fake Karakura Town, Aizen and Gin head through the Dangai in order to reach the real Karakura Town in Soul Society. When they are confronted by the Kōtotsu, Gin warns Aizen to hurry up, for they can do nothing to stop it. Walking up to it, Aizen allows it to collide with him, leaving himself unharmed and the Kōtotsu destroyed. Aizen invites a surprised Gin to carry on with him towards Soul Society.
Back in the Fake Karakura Town, Isshin Kurosaki, hobbling towards Ichigo, headbutts him to pull him out of his state of awe. As Ichigo says their situation is hopeless, for they cannot defeat Aizen with such an amount of Reiatsu, Isshin, realizing Ichigo can sense Aizen's Reiatsu, tells him to come with him, for if he does not, all of Karakura Town will be destroyed and his friends will die. As Ichigo regains his resolve, the two open a Senkaimon. 
Meanwhile, in Soul Society, Aizen notes they did not end up at Karakura Town, but rather a little ways away from it. Gin asks Aizen to not make it sound like it was his fault, for it was Aizen's destroying of the Kōtotsu which made them land here. As Aizen admits this is true, the two walk towards Karakura Town.
In the Dangai, Isshin and Ichigo run towards Soul Society when Isshin, stopping, notes he cannot sense the Kōtotsu. Saying this gives him an opportunity to have Ichigo learn Saigo no Getsuga Tenshō, Isshin reveals the Dangai is cut off from time and space, and time flows faster here, which means spending considerable time in here will result in little time passing outside. As Isshin tells Ichigo he will stop the current, Ichigo enters Jinzen.
Waking up in Karakura Town, Keigo Asano, noticing everyone else is asleep, runs into Tatsuki, who has found Chizuru Honshō and Michiru Ogawa, both of which are sleeping too. As each of them carries one of the girls, they decide to explore the area. At the same time, Aizen and Gin arrive at the border of the town.
Ichigo awakes in his inner world, which is submerged in water, and is met by Tensa Zangetsu, who, attacking him, refuses to teach him Saigo no Getsuga Tenshō. Criticizing Ichigo for having fallen into despair, he pulls the inner Hollow out of his chest. Meanwhile, in Karakura Town, Aizen, finding Tatsuki and Keigo, threatens their lives. Tatsuki tells Keigo to run while she stays behind.
In Ichigo's inner world, the inner Hollow and Tensa Zangetsu merge as the latter states Ichigo's battle shall be with the two of them, for they are the two parts of Ichigo's power. In Karakura Town, as Aizen prepares to kill Tatsuki, Don Kanonji, stepping in to save her, becomes another target for Aizen. They are both saved by the arrival of Lieutenant Rangiku Matsumoto.
As Rangiku tells Don Kanonji to run, Gin asks Aizen if he can talk with Rangiku elsewhere. When Aizen allows it, Gin, grabbing Rangiku, runs off with her. As Aizen notes Gin is an interesting child, Rangiku, breaking free of Gin, tells him she is here because of him and wants answers from him. Raising his Zanpakutō to her, Gin tells her she is in his way.
Returning to Aizen, Gin claims he has killed Rangiku. When Aizen says he had believed Gin held some feelings towards Rangiku, Gin, saying he is a snake and does not have feelings, walks by Aizen. As Aizen tells Gin his plan, Gin, saying it is good, places his hand on Aizen's sword. As he releases Kamishini no Yari from under his sleeve, it impales Aizen. Explaining the only way to escape the abilities of Kyōka Suigetsu, Gin says he had known he was the only one who could kill Aizen. Saying he knew Gin would betray him and had brought him to Soul Society to see how he would do it, Aizen states Gin's attack will not kill him. Explaining the true nature of his Bankai, Gin activates it, leaving Aizen with a gaping hole in his chest.
As Gin goes to grab the Hōgyoku, Aizen tries to stop him. Making it out with the orb, Gin looks at it. As an eruption of Reiatsu reveals Aizen has entered a new form, Aizen states the Hōgyoku is already his whether it is with him or not, approaching Gin, and slashes him across the chest. As the Hōgyoku crumbles in Gin's hand and reforms in the center of Aizen's chest, Aizen, grabbing Gin by the wrist, tears his arm off. Stabbing him in the chest, he, thanking Gin for helping him evolve, throws him into a nearby building. Running to Gin, an unharmed Rangiku cries as she holds his dying body in her arms. Affirming he has failed, Gin apologizes to Rangiku. An older Ichigo arrives, carrying Isshin on his shoulders.
As Ichigo senses Karin Kurosaki and Yuzu Kurosaki are safe, Aizen notes he cannot feel any Reiatsu coming from him. Noticing the strength in Ichigo's eyes, Gin decides he can leave the rest to him. Asking Aizen to fight somewhere else, Ichigo pushes him to the outskirts of the town. 
As Ichigo and Aizen fight, the latter speaks of the superiority of his evolution and the power he has gained. When Ichigo surprises him by stopping a blow from his Zanpakutō with his bare hand, Aizen uses a full incantation Hadō #90. Kurohitsugi. Shattering it with his hand, Ichigo slashes Aizen with his Zanpakutō. 
Evolving once more, Aizen injures Ichigo's left arm with a large explosion. Deciding to put an end to the battle, Ichigo, activating Saigo no Getsuga Tenshō, recalls the end of his fight with Tensa Zangetsu, in which he allowed himself to be stabbed by the spirit, and Tensa Zangetsu's admission of his wish to protect Ichigo.
Ichigo tells Aizen Saigo no Getsuga Tenshō makes him become Getsuga, but it will cost him his Shinigami powers, which is what it means to be final. As Aizen wonders if Ichigo could have really surpassed him, Ichigo uses Mugetsu, and the sky turns black. 
Surviving Ichigo's attack, Aizen tries to attack Ichigo, whose powers are starting to disappear. When Aizen's Zanpakutō disappears, he claims he has reached a new level of evolution. As a Kidō seal is activated, Urahara, appearing, reveals he implanted this seal when they battled in the Fake Karakura Town. When Urahara states the Hōgyoku has rejected Aizen as its master, Aizen, confronting Urahara about his ideals and the nature of the Soul King, is sealed within the Kidō.
Later, Ichigo talks with Urahara about the recent events. When Urahara says Aizen will be taken to Central 46, Ichigo wonders if the Hōgyoku really rejected Aizen, or if Aizen sought to be nothing other than an ordinary Shinigami. Orihime Inoue, Uryū Ishida, Rukia Kuchiki, Yasutora Sado, and Renji Abarai appear and find Ichigo. When they are all happy to see him and emotional over everything which has transpired, Ichigo, laughing at them, collapses, and everyone rushes to help him while he screams in pain.
10 days later, Aizen is sentenced by Central 46 to 18,800 years in the lowest underground prison. After taunting the judges, they increase his sentence to 20,000 years.  In Soul Society, Captain-Commander Genryūsai Shigekuni Yamamoto chastises Captains Shunsui Kyōraku, Byakuya Kuchiki, and Kenpachi Zaraki for losing their haori as Jūshirō Ukitake notes Soul Society is not ready to replace Yamamoto yet. As Captain Tōshirō Hitsugaya trains in a nearby cave, Rangiku reminisces about the death of Gin. In the Human World, Orihime, Sado, Uryū, and Rukia look over Ichigo as he awakens from a month-long sleep. Saying they know Ichigo lost his powers, Rukia explains what has happened to his body. As they all step outside, Ichigo says goodbye to Rukia as she fades from his sight.
|Major Participants||Ichigo Kurosaki • Isshin Kurosaki • Rangiku Matsumoto • Sōsuke Aizen • Gin Ichimaru • Keigo Asano • Tatsuki Arisawa • Chizuru Honshō • Michiru Ogawa • Tensa Zangetsu • Hollow Ichigo • Don Kanonji • Mizuiro Kojima • Zennosuke Kurumadani|
|Events||Arrival in Karakura Town • Gin Ichimaru vs. Sōsuke Aizen • Ichigo Kurosaki vs. Sōsuke Aizen|