Actually, yeah, now that I read the thing again, there is actually no talk of a ninth person.

-black-haired adolescent gets watched
-androgynous person watches
-knight in white armor protects
-girl is protected
-another (or same) girl kills
-blond guy watches colorful man, is killed
-old man watches colorful man, lives
-colofrul man is watches

Out of this, we know that five people performed actions - the androgynous person, the knight (supposedly male), the girl (non-descript), the old man, and Seifer (who died). We also have two to three more people who had actions performed on them. There's the adolescent, the colorful man, and the girl, if she isn't the same girl that was the killer.

That means, there were 7 to 8 people described, depending on whether there was one or two little girls. That means, we have no tangible evidence on who on or two people are.

The people who revealed their identities after the murder were Scruffington, FFNut, and Shauna. Honestly, the smartest move in this case, if you were to lie about your identity, would be to reveal yourself as someone who isn;t the killer, nor appeared in the description. That way, you can take on a false identity without risking being exposed as a fraud. Nutty and Scruffy both revealed their identities as girls, but if both of the references to a girl in the description pertain to one character, we could potentially have two more girls that haven't been revealed. Therefore, Shauna could actually be another girl - the one who actually did the murder. Or perhaps just another girl but she still chose to lie in order to protect herself.