hashira react to themselves

Well, several hashira died. For example, Gyomei Himejima sacrificed himself in a fierce battle.

Some MHA characters might be flattered. For example, Midoriya would probably be really excited and take it as a sign of how much he's inspired people. He might even look for positive lessons in the fanfiction to improve himself.

Yes, Tanjiro eventually becomes a Hashira in the manga after going through many challenging battles and growth.

Not all of them died. Some Hashira managed to survive until the end of the manga.

Inosuke doesn't become a Hashira in the manga. The story progresses with him having other significant experiences and achievements instead of achieving that specific position.

It's hard to give an exact number. Different story arcs and battles led to the deaths of multiple hashira. Some died heroically, while others met their fate in unexpected ways. The count changes as the manga progresses.

Yes, she does. But it happens under specific circumstances and for particular reasons related to the plot.

Definitely not. Genya remains outside the ranks of Hashira throughout the manga. This is because of a combination of factors such as his skills, experiences, and the overall direction of the story.

Yang would likely have a big reaction. If the fanfiction shows her in a cool fight scene, she'd be all for it and might even show it off to her friends. But if it portrays her in a negative or weak way, she'd be really annoyed.

Tina, as a strong - willed Auror, might initially be skeptical. She'd be worried about the accuracy of the fanfiction in terms of the real wizarding world she knows. But after some thought, she might realize it's just a bit of fun for the fans and start to see the charm in it. She could even start to correct some of the inaccuracies in a friendly way if she ever had the chance to interact with the fanfiction writers.