An artifact known as the "King's Seal" is stolen during tranport from the Soul Society by an unidentified Soul Reaper and two Arrancar resembling girls who control fire and lightning. During the attack, Toshiro Hitsugaya corner and seems to recognize the Soul Reaper, who immediately stabs him in the stomach. In the middle of battle, Hitsugaya abandon his post to purue him and leaves his squad behind to fend for themselves. After the battle, The Soul Society suspects Hitsuguya of treason and order his immediate capture. The whole 10th Squad is then put on house arrest at which time they can surmise whether or not the division should be abolished. With the whole of Soul Society looking for Hitsugaya, Ichigo as a soul reaper on patrol accidentally stumbles upon Squad 2 Captain Soifon while she is conducting an investigation of the tranport site. Soifon informs him of the events happening in the Soul Society and dispels the kido surrounding them. As Soifon disappear with her crew, ...

The 10th Division, led by Tōshirō Hitsugaya and Rangiku Matsumoto are sent to escort an artifact known as the "King's Seal" or "Oin", which is stolen during transport from the Soul Society by an unidentified and masked Soul Reaper and two mysterious Arrancar resembling girls who control fire and lightning. During the attack, Hitsugaya corners and seems to recognize the Soul Reaper, who wounds him and leaves. In the middle of battle, Hitsugaya abandons his post to pursue him and leaves his squad behind to fend for themselves. After the battle, the Soul Society suspects Hitsugaya of treason and orders his immediate capture. The whole 10th Squad is then put under house arrest at which time they can surmise whether or not the division should be abolished.

With the whole of the Soul Society searches for Hitsugaya, Ichigo Kurosaki patrols and accidentally stumbles upon 2nd Division Captain Soi Fon, who conducts an investigation of the transport site and informs him of the events happening in the Soul Society and dispels the kido surrounding them. As Soi Fon disappears, Uryu Ishida meets with Ichigo and Tōshirō makes his presence known and passes out in front of them. Tōshirō wakes up in Ichigo's house, replaces his captain's robe with the thief's cloak, and asks Ichigo to step aside. In the midst of their discussion, Ichigo is attacked by the two previous arrancar before he can force the issue. Tōshirō escapes and continues to avoid an attempt of capture by Izuru Kira and Shūhei Hisagi, and things only look worse when the deviated Soul Reaper thief named Sōjirō Kusaka uses Hyōrinmaru, a zanpakutō with identical powers to Hitsugaya's, to injure 8th Division Captain Shunsui Kyōraku. The 6th Division is sent in to investigate this attack, with Byakuya Kuchiki confirming it to be done by Hyōrinmaru. Tōshirō's capture is then made top priority and his execution is approved.

Meanwhile, back in the human world, Rukia meets Ichigo. The group, along with Ishida, Orihime Inoue and Yasutora Sado exchange information, and Rukia reveals rather surprising, in-depth knowledge of Hitsugaya's personality, as well as some rather accurate guesses as to what Hitsugaya plans to do next. During the talk, Ichigo realizes what might be troubling Hitsugaya and leaves to find him. Through his wandering to avoid capture, Tōshirō eventually manages to track Sōjirō down, where it is revealed that the two managed to manifest the same zanpakutō. Because it is impossible for the same zanpakuto to be wielded in Soul Society, the two were forced to fight to the death by the Central 46 Chambers of Soul Society. Tōshirō did not wish to fight, but was left with no other option as Kusaka attacked, claiming that he was the only one worthy of Hyōrinmaru. In the fight, Kusaka is defeated by Tōshirō and the authorities concluded that Tōshirō was the true owner of Hyōrinmaru, with the Military Corps carrying out his execution. Cursing Soul Society and its authorities, Kusaka died and was reborn in Hueco Mundo, where he became a hollow and started his plans of revenge against the Soul Society. Once he learned of the King's Seal and its powers, which allows the user to freely manipulate time, space and matter within a small space, he leapt at the opportunity to settle the score with both Hitsugaya and the Soul Society.

Using the King's Seal, Sōjirō teleports Tōshirō and himself to Sōkyoku Hill in the Soul Society, needing the power of Tōshirō's bankai to break the seal. They are confronted by Ikkaku Madarame, Renji Abarai and Yumichika Ayasegawa. As all Soul Reapers led by Captain-Commander Genryūsai Shigekuni Yamamoto appear on top of the hill. They attack Tōshirō and Kusaka but are thrown back when Ichigo and Rukia intervene, having just arrived in Soul Society. In front of everyone, Tōshirō refuses and Sōjirō breaks the seal himself, having gained enough strength to do so himself, after which he transforms into a giant dragon-like creature made of ice. Kenpachi Zaraki attacks and is defeated by the Dragon Kusaka, who then proceeds to mould the Soul Society's landscape at will. However, because he lacks the control which Tōshirō possesses, the power goes berserk and threatens to destroy the Soul Society. The Soul Reapers try to attack Kusaka all at once, but are repelled by the immense powers of the King's Seal. Encountering Rangiku who had recovered his Captain's Robe from Renji given from Ichigo, he accepts it. Ichigo and Rukia meet up with them and are joined by Renji, Ikkaku and Yumichika. A hoard of hollows appears out of Kusaka's castle which he had generated out of the Kings' Seal, and Yoruichi Shihoin and Soi Fon appear to defeat them. The group then splits up into two, and they both scale there. Battling with various Hollows, Menos and Adjuchas, they each formulate a strategy to attack Kusaka who is at the centre of the castle. Ichigo uses his Visored form while Tōshirō activates Bankai and they both storm up to the central tower, destroying Sōjirō's dragon-like bankai form. In one last clash, Tōshirō impales Sōjirō who asks an incomplete question and finally understands that he really was not worthy of Hyōrinmaru. Tōshirō clears all charges and the King's Seal is restored, allowing him to finally put his past to rest.

After the credits, he and Rangiku visit Kusaka's grave, where Rangiku's lazy nature infers that the 10th Division is reformed.