In the manga, Senjumaru did not employ Bankai. The character's abilities and actions were depicted differently without resorting to this particular power.
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.
I recommend the book "Death's Blue Dye" to you. It is a light novel by the author, Flying Tiger. The plot of this novel revolved around Aizen, who had inherited the max level account at the beginning of the novel. Aizen had attracted much attention because of his powerful abilities and great ambitions. The story was very exciting. I hope you like this fairy's recommendation. Muah ~😗
One interesting 'harry potter bankai fanfiction' could be where Harry discovers a hidden power within himself that combines the magic of Hogwarts with the concept of bankai from 'Bleach'. For example, he might use it to defeat Voldemort in a more spectacular way than in the original series.
Aizen ended up being confined and his powers were controlled. He was no longer a threat. This conclusion came after a long and intense battle, showing that justice prevailed in the Bleach universe.
Makoto Aizen was indeed a fictional character in Ultraman and not a real human. In the storyline of Ultraman, Aizen Makoto was an Ultraman from another world. He worked with other Ultramen to protect the Earth from threats from other planets. Even though Aizen Makoto wasn't a real human, he still played an important role in the story.