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.
Since I'm not very familiar with specific 'Shinji Bankai' light novels, generally, light novels often have unique characters. Maybe in these novels, the characters related to 'Shinji Bankai' have distinct personalities and abilities.
I'm not sure which specific 'Shinji Bankai' light novels there are. You could try searching on major e - book platforms or specialized Japanese literature websites.
Naruto might use Bankai in a more physical and direct way compared to Bleach characters. Since Naruto is used to combat with his body and chakra - enhanced attacks, his Bankai could be more like a physical transformation rather than the more spiritual manifestations in Bleach. For example, instead of a spectral form, his Bankai could be a physical enhancement of his body with the Zanpakuto's power.
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.
Yes, there are likely some fanfics out there where Naruto has Bankai. Fanfic writers often like to combine different elements from various anime. They might create a scenario where Naruto somehow acquires Bankai abilities from the Bleach universe. However, the quality and exact nature of such fanfics can vary greatly.
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.