Eeep! Um... well, I think it's a fairly safe bet 
(looking at the quality of the cel) that it's 
from somewhere in Next or Try... but I can't get 
any closer than that. -_-; It's so much easier 
when the characters are in unusual poses or have 
other characters nearby, or have costume 
alterations... I can't quite identify my sketches 
of Lina for a similar reason. 

But if it was easy, there wouldn't be a question, 
would there? ^_^ Sorry I'm not more helpful 
*wrings hands* however... maybe that's a good 
excuse to re-watch the series again. (As if I 
needed one!) Gotta finish CCS first though... :)