The backdrop of the Bleach TYBW arc had the perfect recipe for all the characters to come together, and unite against the unfathomable force of Quincy. It was a chance for many characters in Bleach to redeem themselves and unleash their full potential. Since the stakes were so high, many wondered why none of the Vizard Captains used their Hollowfication abilities in the Blood War.
This is something that especially concerns the reinstated Captains, namely Shinji Hirako, Kensei Muguruma, and Rojuro Otoribashi. While being incredibly strong in their own right as Captains, Shinji, Kensei, and Rose had an added bonus that the other captains of the Gotei 13 did not have - access to the Hollowfication technique.
Possible reasons why the Vizard Captains couldn't use their Hollowfication powers in Bleach TYBW
Lack of opportunity to use Hollow Mask in the blood war
Given that Hollow reiatsu is poisonous to the Quincies, and the Hollow Powers could enhance their strength, it should have been the go-to choice for the vizard captains to use their Hollow Mask in the Blood War.
Fans have seen other Vizards, namely Hiyori, Love, and Lisa use their Hollow masks against Gerald Valkyre in the Bleach TYBW arc. Furthermore, Mashiro, the 9th Division co-lieutenant was also seen using her Hollow Mask while training Shuhei after the first Quincy Invasion.
However, none of the Vizard captains who were reinstated used their Hollow Mask. So, the question remains: Why did the vizard captains refrain from using their Hollow Mask during their battles against the Quincy?
There are a few possible reasons for this as Tite Kubo, the author, hasn't provided an exact answer for the same. There's a popular theory in the fandom that Tite Kubo simply forgot that the vizards could use their hollow mask. However, this is quite improbable as otherwise, he wouldn't have shown Hiyori, Lisa, Love Aikawa, and Mashiro using their Hollow Mask in the Bleach TYBW arc.
There's another possibility that the Vizard Captains, namely Shinji, Kensei, and Rose didn't have a proper opportunity to use their Hollowfication abilities in the arc. In Bleach TYBW episode 16, the setting was perfect for Shinji to use his Bankai, which he did.
Next, he confronted Bambietta Basterbine and bamboozled her with his Zanpakuto's Shikai release, Sakanade. Since Bambietta had no answer to his Zanpakuto's powers, Shinji didn't necessarily need his Hollow Mask.
Moreover, when Bambietta awakened her Vollstandig and fired reishi bombs at Shinji, the latter didn't have a chance to fight back. There were many other instances in the Bleach TYBW manga when Shinji appeared but didn't have a proper chance to use his Hollow Mask.
Similarly, Kensei outright used his Bankai, and severely wounded Mask de Masculine. However, he couldn't intercept the Superstar Sternritter's counterattack, and as a result, didn't have a chance to put on his Hollow Mask.
While Rojuro Otoribashi could potentially use his Hollow Mask against Mask de Masculine, he chose to unleash his Bankai Kinshira Butodan instead. He could have won the battle if he hadn't spilled the secret to his Bankai. In the end, it was too late for him to react to Mask de Masculine's Star Flash and use his Hollow Mask.
Using a Hollow Mask also greatly drains its user. As a result, it's possible that the Vizard Captains didn't feel the need to use their Hollowfication abilities.
It wasn't possible for the Vizard Captains to use both Hollow Mask and Bankai at the same time
If Shinji, Kensei, and Rose were given a choice between using Hollow masks and Bankai, they would have chosen Bankai simply because of its power. However, is it possible to enhance the power further using Hollow Mask?
While this is only a theory, there's a possibility that they couldn't use the Bankai and Hollowfication techniques at the same time in Bleach TYBW. Aizen in Turn Back the Pendulum Arc explicitly mentioned that the Vizards were a failed experiment.
Tosen Kaname could use his resurrection-like technique in addition to his Bankai because he was more of a 'complete' hybrid. However, this is only a theory and there is no concrete evidence to support it.
Vizard Captains were perhaps restricted from using their Hollowfication abilities by the Central 46
In the Bleach community, this theory makes the most sense, considering all the facts related to the Vizards. After the events of the Turn Back the Pendulum Arc, the Vizards were exiled from the Soul Society. However, later in the story, some of them were reinstated to fill the void created by Aizen, Gin, and Tosen.
Perhaps, one of the conditions for their reinstatement was that they would never use their Hollow powers as Captains. In other words, they got their old positions back on the condition that they would never use their Hollow Mask.
One may then wonder why Mashiro, who became the Co-lieutenant of the 9th Division, used her Hollow Mask during Shuhei's Bankai training. There's a possibility that the law only applied to those who were reinstated as Captains.
There's another theory that states that the Law only applies within the boundaries of the Seireitei. As a result, Kensei Muguruma took Shuhei Hisagi all the way to Rukongai for the Bankai training and had Mashiro hollowfied.
All said and done, it's still a bit baffling to think that none of the Vizard Captains used their Hollow Masks in the Blood War during life-and-death situations. It's almost as if the Vizards were a wasted potential in Bleach TYBW.
Stay tuned for more Bleach anime news as 2023 progresses.