User blog comment:Shinjojin/New Rokushiki Robin artwork 11/30/12/@comment-972068-20121201154034/@comment-3449450-20121201154551

Actually, it's the enemies that are in the cage. But yeah, I can see people getting the same impression you had due to Robin's expression. :(

In the orignal rough sketch that Cann drew, Robin was actually smiling while looking at her enemies trying to break out.

http://i4.photobucket.com/albums/y114/ccann/artwork%20posts/sketchrobin2.jpg