Ichigo Kurosaki is, of course, the most important character in Bleach, as he is the protagonist and main hero of the story who always ends up saving the day. As his story evolved, his powers and abilities evolved, and by the time the story ended, Ichigo had undergone several phases and transformations. This was also reflected in his Bankai, his most powerful technique. But, at the beginning of the Thousand-Year Blood War Arc, we discovered that the Quincy could steal the Shinigami’s Bankai, with one exception – Ichigo! This article will explain why Ichigo’s Bankai could not be stolen in the series.
Ichigo’s Bankai could not be stolen because it was actually a manifestation of his Quincy Powers. Ichigo is a Quincy, partially due to his mother being one, so his powers are a combination of Quincy and Shinigami’s powers at the same time. The Bankai he activated when he was fighting Ebern was actually a manifestation of his Quincy Powers, and since Quincy could only steal Shinigami Bankai, Ebern was not able to steal it.
The rest of this article will, of course, be focused on Ichigo’s Bankai and his innate dual abilities in the series, from which you can deduce why Ichigo’s Bankai could not be stolen in the series. The rest of this article will expand on the answer given above, and you will be able to fully understand everything that happened in the series based on that. We have to warn you, though, that the article will contain spoilers from the series, so be careful how you approach it ultimately.
Ichigo’s Bankai could not be stolen because it was a manifestation of his Quincy powers, and the Quincy could only steal purely Shinigami Bankai
Going back to the beginning of the Quincy War saga, in which the Soul Society will have to fight against Yhwach and his Sternritter, the whole saga actually started with the Arrancar Asguiaro Ebern coming to Ichigo’s room and starting a fight with the young boy. Although Ebern was an Arrancar, he was actually in service of Yhwach’s Quincy Army, which is why he had been given some tools and powers that made him look more like a Quincy, despite actually being a Hollow.
Ebern was no match for Ichigo, but it turns out he had a vile plan – he wanted Ichigo to activate his Bankai so he could, seemingly, steal it. This was later confirmed to be true when the Sternritter invaded the Seireitei, stealing several Bankai, including Toshiro’s and Byakuya’s. But, while the Sternritter in the Seireitei were successful in their endeavors, Ebern had no luck with Ichigo.
Sure, Ichigo activated his Bankai at one point, but when Ebern was about to steal it, the attempt failed. While Ebern did not know why it failed, Ichigo did not even know what was going on, so he simply defeated the Arrancar, which he would have done had he not been summoned back to the Wandenreich.
So, after learning about these powers later on – as Mayuri confirmed that the Sternritter were capable of doing – we knew that Ebern tried to steal Ichigo’s Bankai, but his Bankai was the only one that was not stolen; okay, most of the Captains preserved theirs as well, but that is only because they did not activate them – if a Sternritter activated the process, he was, ultimately, successful except in Ichigo’s case. At that moment, it was not fully clear why that happened, but further chapters (episodes) provided us with an answer and an explanation.
Namely, and we must go back in time here, Ichigo’s past contains the answer. We already knew that Ichigo had both Hollow powers (as we’ve seen White Ichigo) and Shinigami powers (as his father was a Shinigami and the former Captain of Division 10), but he also had another set of powers. Namely, this was something that Aizen was about to reveal during their clash in Fake Karakura Town before being interrupted by Isshin, but the truth would be revealed eventually. Namely, Ichigo’s mother, Masaki Kurosaki, was a Quincy; thus, Ichigo was also partially a Quincy.
Knowing that his Zanpakuto, Zangetsu, had a dual nature – that of a Hollow (White Ichigo) and the Old Man Zangetsu everyone thought was a Shinigami – everything adds up piece by piece. Namely, it turned out that Old Man Zangetsu wasn’t actually a manifestation of Ichigo’s Shinigami powers but rather a manifestation of his Quincy powers, which explains why Old Man Zangetsu looks so much like Yhwach, especially when he was younger.
So, the Bankai Ichigo activated in front of Ebern was actually a manifestation of his Quincy powers and not a manifestation of his Shinigami powers. Knowing this fact makes it easier to understand why Ebern failed in stealing the Bankai.
Namely, the Medallion used by Ebern and the Sternritter could steal a Bankai; that much is clear. But, as it turned out, the Medallion only worked on Shinigami powers and not on Quincy powers. Because Yhwach cherished his Quincy heritage too much, the powers of the Quincy, the special ones at least, couldn’t be used against another Quincy (this is why Ichigo was able to get out of Opie’s “The Jail” when his Quincy powers kicked in).
So, while the Medallion could steal a Bankai that was a manifestation of a Shinigami’s own Shinigami powers, whose nature is different from that of the powers of a Quincy, it was useless against Ichigo’s Bankai, as Ichigo’s Bankai was actually a manifestation of his own Quincy powers.
These powers had been passed down to Ichigo by his mother, Masaki, which also explains the dual nature of his powers and his Zanpakuto. This fact will later play a major role when Nimaiya actually reforges Ichigo’s broken Zanpakuto.