In the 'weak hero novel', the story might revolve around a not - so - physically - strong hero. This hero could be an underdog in a world full of stronger or more intimidating characters. He may use his wits, like devising clever strategies to deal with the problems. For example, when facing bullies, instead of using brute force, he might outsmart them with his knowledge or unique skills, which makes the story really interesting.
I'm not sure exactly as there could be various main characters depending on the specific 'weak hero novel'. But generally, there would be the weak hero himself, perhaps a bully or two who act as antagonists, and maybe some friends or allies that the weak hero makes along the way.
There could be many. For example, some fanfictions might focus on the backstories of the characters that were not fully explored in the original. Maybe a story about how one of the characters got into their fighting style before coming to the school.
Gray is often a popular one. His cool and mysterious demeanor makes him a great focus for fanfiction writers. They can explore more about his past traumas and how he overcomes them.
Sorry, I don't know off the top of my head. But you could try looking through online discussions or the official website of the novel for the correct chapter.
Well, in chapter 28 of the novel, the hero discovers a hidden secret that changes everything. There's also an intense battle scene and some character development.