Naruto's bankai might incorporate his fox - like features. Given his connection to the Nine - Tails, his bankai could have a large, fiery fox form that enhances his speed and strength, much like how his Nine - Tails Chakra Mode works. His zanpakuto could also be related to the rasengan, perhaps having the ability to fire off rasengan - like attacks from the blade or using the spinning energy as a defensive mechanism.
In the context of the relevant novel, Aizen's Bankai is a very powerful and important aspect. It represents a high level of his power and is often a crucial factor in the plot development, especially in battles and power - struggle scenarios within the story.
Yes, in some fanfictions, Naruto is given a Bankai. Fanfiction writers often like to cross - over different anime concepts. They might give Naruto the power of a Bankai from 'Bleach' to create unique and interesting storylines. This can lead to some really cool battles and character developments that you wouldn't see in the original Naruto series.
In fanfics, anything is possible. Since it's a fictional creation, an author could write a scenario where Naruto has the ability to use Bankai. However, in the original Naruto and Bleach universes, their powers are completely separate, with Naruto having chakra - based ninja abilities and Bankai being a high - level power in the Bleach world.
In the manga, Senjumaru did not employ Bankai. The character's abilities and actions were depicted differently without resorting to this particular power.
One possible plot for a 'naruto bankai fanfic' is that there is a prophecy in the Naruto world that a power from another realm will be the key to saving it from destruction. Naruto is chosen to seek out this power. He discovers the concept of Bankai in the Bleach realm. After many trials and training sessions with some friendly Shinigami, he unlocks his own version of Bankai, which combines his chakra and the spiritual energy of Bankai. With this new power, he unites the villages like never before as they face a common, extremely powerful enemy.
Shinji did use his Bankai in the manga. It was a crucial moment that turned the tide of the fight. The Bankai's power and unique abilities were showcased, adding an exciting element to the story.