[@Shiyonichi]: Right, form analysis...
[list][*]I think at her core, your character is a bit too tonally dissonant from the rest of the cast. I can feasibly see child soldiers in the criminal underbelly; that's a very commonplace thing. But the specific circumstances behind the character's inception (the whole kodoku-esque creation method in particular) leaves a bit of an unwanted taste in my mouth, as the very specific trait of "possibly bloody psychopath hitman child murderer" with no real narrative weight behind it isn't something I think would fare well in the world...
And, if I'm going to be honest, feels a bit one-note as written. A boss with a high difficulty spike who appears out of nowhere with no real meaningful history feels more like... Well, just that. I'd point to, say, SMT3's Matador, for example. People remember that boss because you're forced to fight them on the back foot and kind of just sucker punches you because you don't expect them, but otherwise isn't exactly memorable as a [i]character[/i].
[*]The circumstances behind her entry into the school in this 'timeline' feel a bit contrived. While I would agree that she would need an excuse to get off the streets to attend, "saving the headmaster's kid and getting adopted by him as a result" seems a bit too convenient. There are probably better, more reasonable routes to doing so that would lead to a character who ended UP with a reputation as a damn good killer (and you don't need to be put into a tournament to the death to facilitate being good at killing, if I'm being completely honest; it gets you the person who is the best at [i]surviving[/i], not killing), and I'd recommend considering those routes. Easy examples include things like "forced nobility to adopt her into the family" or "missing child now found" and so on and so forth, but I'm not going to force anything in that regard.[/list]

For the reasons above, I'm choosing to reject the form as it is right now.