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.
One possible plotline could be that Tsukuyo becomes Gintoki's caretaker in a way. She helps him navigate the world around him, and in the process, their relationship deepens. Gintoki, who is used to being independent, has to rely on Tsukuyo, and this new dynamic changes their feelings for each other.
I'm not sure about specific fanfics where Gintoki is blind in relation to Tsukuyo. However, you can try searching on fanfic platforms like Archive of Our Own or Fanfiction.net. Use the relevant tags such as 'Gintoki', 'Tsukuyo', and 'blind' to narrow down your search.
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.
We should avoid the bdsm part as it may involve inappropriate content. For Gintoki - related fanfics, they might show his growth as a character over time. Maybe start from his days as a freeloader to becoming more responsible in certain situations. His sarcastic remarks and his ability to get out of tight situations in a comical way are also things that might be emphasized in a fanfic.
In fanfic, female Gintoki often retains her laid - back attitude. She still loves her strawberry milk and has that easy - going yet sarcastic personality. For example, in some fanfics, she'll crack the same type of jokes as the male Gintoki.
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.